Artificial intervertebral disc trial having a controllably separable distal end

ABSTRACT

Instrumentation for implanting an artificial intervertebral disc includes a dynamic trial for distracting an intervertebral space and/or determining the appropriate size of disc to be implanted, which dynamic trial includes a shaft, at least two distal extensions coupled to the shaft, a bifurcated trial having a first trial half of the bifurcated trial coupled to a first of the extensions and having a second trial half of the bifurcated trial coupled to a second of the extensions, and a pin located between the extensions, wherein movement of the pin in a distal direction increases a separation between the extensions, and wherein varying the separation between the extensions varies a separation between the trial halves.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] The present application is a continuation application of U.S.patent application Ser. No. 10/282,356 (filed Oct. 29, 2002) entitled“Instrumentation and Methods for use in Implanting an ArtificialIntervertebral Disc”, which is a continuing application of U.S. patentapplication Ser. No. 10/256,160 (filed Sep. 26, 2002) entitled“Artificial Intervertebral Disc Having Limited Rotation Using a CapturedBall and Socket Joint With a Solid Ball and Compression Locking Post”,which is a continuing application of U.S. patent application Ser. No.10/175,417 (filed Jun. 19, 2002) entitled “Artificial IntervertebralDisc Utilizing a Ball Joint Coupling”, which is a continuing applicationof U.S. patent application Ser. No. 10/151,280 (filed May 20, 2002)entitled “Tension Bearing Artificial Disc Providing a Centroid of MotionCentrally Located Within an Intervertebral Space”, which is a continuingapplication of both U.S. patent application Ser. No. 09/970,479 (filedOct. 4, 2001) entitled “Intervertebral Spacer Device Utilizing aSpirally Slotted Belleville Washer Having Radially Extending Grooves” aswell as U.S. patent application Ser. No. 10/140,153 (filed May 7, 2002)entitled “Artificial Intervertebral Disc Having a Flexible Wire MeshVertebral Body Contact Element”, the former being a continuingapplication of U.S. patent application Ser. No. 09/968,046 (filed Oct.1, 2001) entitled “Intervertebral Spacer Device Utilizing a BellevilleWasher Having Radially Extending Grooves” and the latter being acontinuing application of both U.S. patent application Ser. No.09/970,479 (detailed above) as well as U.S. patent application Ser. No.10/128,619 (filed Apr. 23, 2002) entitled “Intervertebral Spacer Havinga Flexible Wire Mesh Vertebral Body Contact Element”, which is acontinuing application of both U.S. patent application Ser. No.09/906,119 (filed Jul. 16, 2001) and entitled “Trial IntervertebralDistraction Spacers” as well as U.S. patent application Ser. No.09/982,148 (filed Oct. 18, 2001) and entitled “Intervertebral SpacerDevice Having Arch Shaped Spring Elements”. All of the above mentionedapplications are hereby incorporated by reference herein in theirrespective entireties.

FIELD OF THE INVENTION

[0002] This invention relates generally to systems and methods for usein spine arthroplasty, and more specifically to instruments fordistracting an intervertebral space, inserting and removing trialartificial intervertebral discs, and inserting, impacting,repositioning, leveling and extracting artificial intervertebral discs,and methods of use thereof.

BACKGROUND OF THE INVENTION

[0003] The bones and connective tissue of an adult human spinal columnconsists of more than twenty discrete bones coupled sequentially to oneanother by a tri-joint complex that consists of an anterior disc and thetwo posterior facet joints, the anterior discs of adjacent bones beingcushioned by cartilage spacers referred to as intervertebral discs.These more than twenty bones are anatomically categorized as beingmembers of one of four classifications: cervical, thoracic, lumbar, orsacral. The cervical portion of the spine, which comprises the top ofthe spine, up to the base of the skull, includes the first sevenvertebrae. The intermediate twelve bones are the thoracic vertebrae, andconnect to the lower spine comprising the five lumbar vertebrae. Thebase of the spine is the sacral bones (including the coccyx). Thecomponent bones of the cervical spine are generally smaller than thoseof the thoracic spine, which are in turn smaller than those of thelumbar region. The sacral region connects laterally to the pelvis. Whilethe sacral region is an integral part of the spine, for the purposes offusion surgeries and for this disclosure, the word spine shall referonly to the cervical, thoracic, and lumbar regions.

[0004] The spinal column is highly complex in that it includes thesemore than twenty bones coupled to one another, housing and protectingcritical elements of the nervous system having innumerable peripheralnerves and circulatory bodies in close proximity. In spite of thesecomplications, the spine is a highly flexible structure, capable of ahigh degree of curvature and twist in nearly every direction.

[0005] Genetic or developmental irregularities, trauma, chronic stress,tumors, and degenerative wear are a few of the causes that can result inspinal pathologies for which surgical intervention may be necessary.With respect to the failure of the intervertebral disc, and theinsertion of implants and/or height restorative devices, several methodsand devices have been disclosed in the prior art that achieveimmobilization and/or fusion of adjacent bones by implanting artificialassemblies in or on the spinal column. More recently, the development ofnon-fusion implant devices, which purport to permit continued naturalmovement in the tri-joint complex, have provided great promise as apreferably alternative to fusion devices. The region of the back thatneeds to be corrected, as well as the individual variations in anatomy,determine the appropriate surgical protocol and implantation assembly.Generally, the preparation of the intervertebral space for the receiptof fusion or non-fusion devices involves removing the damaged discmaterial and thereafter distracting the adjacent vertebral bones totheir appropriate distance apart. Once the proper height of theintervertebral space is restored, the fusion or non-fusion device can beimplanted.

[0006] It is an object of the invention to provide instrumentation andmethods that enable surgeons to more accurately, easily, and efficientlyprepare the intervertebral space and implant fusion or non-fusiondevices. Other objects of the invention not explicitly stated will beset forth and will be more clearly understood in conjunction with thedescriptions of the preferred embodiments disclosed hereafter.

SUMMARY OF THE INVENTION

[0007] The preceding objects are achieved by the invention, whichincludes static trial artificial intervertebral discs (sometimesreferred to herein as a “static trial”), a static trial artificialintervertebral disc holder (sometimes referred to herein as a “statictrial holder”), a dynamic trial artificial intervertebral disc(sometimes referred to herein as a “dynamic trial”), an artificialintervertebral disc inserter/impactor (sometimes referred to herein asan “inserter/impactor”), an artificial intervertebral discrepositioner/extractor (sometimes referred to herein as a“repositioner/extractor”), and an artificial intervertebral disc leveler(sometimes referred to herein as a “leveler”).

[0008] More particularly, the systems and methods disclosed herein areintended for use in spine arthroplasty procedures, and specifically foruse with the systems and methods described herein in conjunction withthe systems and method described in U.S. patent application Ser. No.10/256,160 (filed Sep. 26, 2002) entitled “Artificial IntervertebralDisc Having Limited Rotation Using a Captured Ball and Socket Joint Witha Solid Ball and Compression Locking Post” (hereinafter referred to as“the '160 application”) as well as U.S. patent application Ser. No.09/906,127 (filed Jul. 16, 2001) entitled “Insertion Tool For Use WithIntervertebral Spacers” (hereinafter referred to as “the '127application”), both applications of which are mentioned above. However,it should be understood that the systems and methods described hereinare also suitable for use with other systems and methods withoutdeparting from the scope of the invention.

[0009] For example, while the static trials described herein areprimarily intended for use in determining the appropriate size ofparticular embodiments of the artificial intervertebral disc implantsdescribed in the '160 application to be implanted (or whether aparticular size can be implanted) into the distracted intervertebralspace, they can also be used for determining the appropriate size of anyother suitably configured orthopedic implant or trial to be implanted(or whether a particular size can be implanted) into the distractedintervertebral space.

[0010] And, for example, while the static trial holder described hereinis primarily intended for use in holding, inserting, removing, andotherwise manipulating the static trials described herein, it can alsobe used for manipulating any embodiment of the trial spacers describedin the '127 application (also referred to therein and herein asdistraction spacers), and can also be used for manipulating any othersuitably configured orthopedic device.

[0011] And, for example, while the dynamic trial described herein isprimarily intended for use in distracting an intervertebral spaceaccording to the procedures described herein and/or for determining theappropriate size of particular embodiments artificial intervertebraldisc implants described in the '160 application to be implanted (orwhether a particular size can be implanted) into the distractedintervertebral space, it can also be used for distracting anintervertebral space according to other procedures and/or fordetermining the appropriate size of any other suitably configuredorthopedic implant or trial to be implanted (or whether a particularsize can be implanted) into the distracted intervertebral space.

[0012] And, for example, while the inserter/impactor described herein isprimarily intended for use in holding, inserting, removing, impacting,extracting, and otherwise manipulating particular embodiments of theartificial intervertebral disc implants described in the '160application, it can also be used for manipulating any other suitablyconfigured orthopedic implant or trial.

[0013] And, for example, while the repositioners/extractors describedherein is primarily intended for use in repositioning and/or extractingand/or otherwise manipulating particular embodiments of the artificialintervertebral disc implants described in the '160 application, it canalso be used for manipulating any other suitably configured orthopedicimplant or trial.

[0014] And, for example, while the leveler described herein is primarilyintended for use in setting the proper position of, and/or otherwisemanipulating, particular embodiments of the artificial intervertebraldisc implants described in the '160 application, it can also be used formanipulating any other suitably configured orthopedic implant or trial.

[0015] While the instrumentation described herein (e.g., the statictrials, static trial holder, dynamic trial, inserter/impactor,repositioners/extractors, and leveler) will be discussed for use withthe artificial intervertebral disc of FIGS. 1g-n, such discussions aremerely by way of example and not intended to be limiting of their uses.Thus, it should be understood that the tools can be used with any of theartificial intervertebral discs disclosed in the '160 application, orany other artificial intervertebral disc having (or being modifiable ormodified to have) suitable features therefor. Moreover, it isanticipated that the features of the artificial intervertebral disc(e.g., the flat surfaces and accompanying holes) and/or the statictrials (e.g., the cylindrical trunks and flat surfaces and accompanyingholes) that are used by the tools discussed herein to hold and/ormanipulate these devices (such features, it should be noted, were firstshown and disclosed in the '160 application and the '127 application)can be applied, individually or collectively or in various combinations,to other trials, spacers, artificial intervertebral discs or otherorthopedic devices as stand-alone innovative features for enabling suchtrials, spacers, artificial intervertebral discs, or other orthopedicdevices to be more efficiently and more effectively held and/ormanipulated by the tools described herein or by other tools havingsuitable features. In addition, it should be understood that theinvention encompasses artificial intervertebral discs, spacers, trials(static or dynamic), and/or other orthopedic devices, that have one ormore of the features disclosed herein, in any combination, and that theinvention is therefore not limited to artificial intervertebral discs,spacers, trials, and/or other orthopedic devices having all of thefeatures simultaneously.

[0016] More particularly with regard to the static trials describedherein, a plurality of static trials are provided primarily for use indetermining the appropriate size of an artificial intervertebral disc tobe implanted (or whether a particular size of the artificialintervertebral disc can be implanted) into the distracted intervertebralspace (e.g., the artificial intervertebral disc 160 of FIGS. 1g-n).Preferably, for each artificial intervertebral disc to be implanted, aplurality of sizes of the artificial intervertebral disc would beavailable. That is, preferably, a plurality of the same type ofartificial intervertebral disc would be available, each of the pluralityhaving a respective width and depth dimension combination that allows itto fit within a correspondingly dimensioned intervertebral space. Forexample, the plurality of artificial intervertebral discs could includeartificial intervertebral discs having widths being either 35 mm or 40mm, and depths ranging from 14 mm to 18 mm in 1 mm increments, for atotal of 10 discs. Accordingly, preferably, each of the plurality ofstatic trials 100 for use with a particular plurality of differentlysized artificial intervertebral discs would have a respective width anddepth dimension set corresponding to the width and depth of a respectiveone of the plurality of differently sized artificial intervertebraldiscs. For example, the plurality of static trials 100 for use with theset of artificial intervertebral discs described for example couldinclude static trials 100 having widths being either 35 mm or 40 mm, anddepths ranging from 14 mm to 18 mm in 1 mm increments, for a total of 10static trials. It should be understood that the artificialintervertebral discs and/or the static trials 100 can be offered in avariety of dimensions without departing from the scope of the invention,and that the dimensions specifically identified and quantified hereinare merely exemplary. Moreover, it should be understood that the set ofstatic trials 100 need not include the same number of trials for eachartificial intervertebral disc in the set of artificial intervertebraldiscs, but rather, none, one, or more than one trial can be included inthe trial set for any particular artificial intervertebral disc in theset.

[0017] Each of the plurality of static trials preferably furtherincludes features that can be used by the static trial holder (describedbelow), the inserter/impactor (described below), and therepositioners/extractors (described below). With regard to a featurethat can be used by the static trial holder, each static trialpreferably includes a recess that can be gripped by the opposingsemicircular extents of the static trial holder. Preferably, this recessforms an annular groove that establishes a cylindrical trunk between thebaseplates of the static trial, such that the baseplates extend asflanges from either end of the cylindrical trunk. Accordingly,preferably, the opposing semicircular extents each have a thicknesssmaller than the width of the annular groove, and as such fit into theannular groove to grip the cylindrical trunk between them.

[0018] With regard to features that can be used by theinserter/impactor, each static trial (and each artificial intervertebraldisc that the trials approximate) preferably includes an anteriorlyfacing flat surface, flanked by two anteriolaterally facing flatsurfaces (one on each side of the anteriorly facing flat surface), and,to provide for holding of the static trial or disc for an anteriorinsertion approach, a hole spaced from the anteriorly facing flatsurface, the hole having a longitudinal axis parallel to the anteriorlyfacing flat surface. The holding pin of the inserter/impactor fitswithin the hole, and the angled flat surfaces of the static trial ordisc fit against the correspondingly angled flat surfaces of theinserter/impactor, and operation of the inserter/impactor pulls theholding pin toward the flat surface of the inserter/impactor oppositethe pin, to rigidly hold the static trial or disc by the baseplate. Whenthe static trial is held in this manner, rotation of the static trial ordisc about a longitudinal axis (e.g., in the case of the trials, an axisparallel to the longitudinal axis of the cylindrical trunk) relative tothe inserter/impactor is prevented by interference of the corners of thestatic trial's or disc's flat surfaces and the corners of theinserter/impactor's flat surfaces, similar to the manner in which awrench holding a nut prevents rotation of the nut relative to thewrench. Further, the holding of the static trial or disc in this mannerallows for some repositioning of the static trial or disc in theintervertebral space via rotation of the static trial or disc in eitherdirection about the longitudinal axis of the intervertebral space.

[0019] Preferably, both of the baseplates of the static trial or dischave similarly configured flat surfaces, and both baseplates' flatsurfaces fit against the angled flat surfaces of the inserter/impactorto provide for a more secure holding of the static trial or disc by theinserter/impactor. Also preferably, in order to provide for a holding ofthe static trial or disc for two additional (here, anteriolateral)insertion approaches, each static trial or disc also include twoadditional holes, one spaced apart from one of the anteriolaterallyfacing flat surfaces, and the other spaced apart from the other of theanteriolaterally facing flat surfaces. Accordingly, operation of theinserter/impactor can fit the holding pin into either of these twoadditional holes, and hold the anteriolaterally facing flat surface (theone associated with the hole into which the pin is fit) of the statictrial or disc against the flat surface of the inserter/impactor oppositethe pin. It should be understood that preferably, in order to facilitatethese two additional approaches, the angle separating the anteriorlyfacing flat surface of the static trial or disc and one of theanteriolaterally facing flat surfaces of the static trial or disc isequal to the angle separating the anteriorly facing flat surface and theother of the anteriolaterally facing flat surfaces.

[0020] With regard to features that can be used by therepositioners/extractors, each static trial (and each artificialintervertebral disc that the trials approximate) preferably includes atleast two holes extending longitudinally into one of the baseplates ofthe trial or disc from the inwardly facing surface of the baseplate.More than two holes can be used to provide for multiplerepositioning/extracting approaches. Preferably, in order for the samerepositioning/extracting tool to be used for multiple approaches on thesame trial or artificial intervertebral disc, adjacent holes should beseparated by the same distance separating other adjacent holes.

[0021] As discussed in greater detail below with regard to therepositioners/extractors, in order to engage two of the holes, eachrepositioner/extractor has two pins extending in parallel from a centralshaft, perpendicular to the longitudinal axis of the central shaft. Thepins can be inserted into the holes, and pulling or pushing on thecentral shaft along its longitudinal axis when the holes are engagedpulls or pushes the static trial or artificial intervertebral disc inthe intervertebral space. Further, because two holes are engaged, thestatic trial or artificial intervertebral disc can be rotated in eitherdirection about a longitudinal axis passing through the intervertebralspace, by rotating of the central shaft of the repositioner/extractorabout its distal end, about an axis parallel to the longitudinal axes ofthe pins.

[0022] On each repositioner/extractor, the pins are formed on prongsthat extend laterally from the central shaft. The direction of theprongs, and the location of the pins relative to the central shaft,determine the angle or angles of surgical approach for which aparticular repositioner/extractor can be used. Further, the number andlocation of holes further determine the angle or angles of surgicalapproach for which a particular repositioner/extractor can be used.Accordingly, the present invention contemplates a variety ofrepositioner/extractors, and a variety of holes configurations, toprovide the surgeon with a variety of possible surgical approach angles.

[0023] As described in greater detail below, threerepositioner/extractors are illustrated and described (symmetric, offsetleft, and offset right) for example, and, for example, two holeconfigurations are illustrated and described. A first hole configurationincludes the hole configuration described above, that is, three holes onone of the baseplates (e.g., the lower baseplate), the holes beingconfigured so that a first hole is located in the anterior-posteriorplane, and the adjacent (second and third) holes are located inrespective opposing anteriolateral planes on either side of the firsthole. A second hole configuration includes four holes on one of thebaseplates (e.g., the upper baseplate), the holes being configured sothat first and second holes straddle the anterior-posterior plane, athird hole is located so that the third hole and the first hole straddleone of the opposing anteriolateral planes, and a fourth hole is locatedso that the fourth hole and the second hole straddle the other of theopposing anteriolateral planes.

[0024] With further regard to the static trial holder described herein,the static trial holder is provided primarily for use in holding,inserting, removing, and otherwise manipulating the static trialsdescribed herein. Preferably, the static trial holder has a pair ofopposing prongs that open away from one another and close toward oneanother. Each of the prongs has a semicircular extent and thesemicircular extents face one another to define a circular holdingenclosure that is useful for capturing the cylindrical trunk of thestatic trial between them. The prongs are spring biased toward a neutralposition such that the holding enclosure is spring biased to a receptivestate in which the cylindrical trunk can be snapped into (or out of) theholding enclosure by temporarily placing the holding enclosure in anexpanded state (by forcing the cylindrical trunk against the mouth ofthe enclosure) that allows passage of the cylindrical trunk through themouth of the enclosure. Once the cylindrical trunk is in the enclosure,the holding enclosure can be placed in a contracted state, or locked,where the trial is more securely held, so that the trial will not escapethe holding enclosure as it is experiencing greater forces while beinginserted and removed from the intervertebral space. This locking iseffected by rotating a sleeve that surrounds the prongs. The bore of thesleeve is configured to press the prongs together when the sleeve isrotated a quarter turn, and to allow them to separate when the sleeve isagain rotated a quarter turn (in either direction). The sleeve is biasedtoward stopping its rotation at either the “locked” or “unlocked” statesof the holding enclosure, by the cooperation of recesses on theextension's outer surface and corresponding spring plungers radiallydisposed to project from the sleeve's inner surface. It should beunderstood that when the static trial is being held (either when theholding enclosure is in its receptive state or in its contracted state),because the semicylindrical extents fit within the annular groove of thestatic trial, the static trial will not escape from the enclosure alongthe longitudinal axis of the cylindrical trunk. While the static trialholder is discussed herein as primarily used for manipulating the statictrials, it preferably is also useful for manipulating the distractionspacers described in the '127 application, in that the semicircularextents of the pincers preferably also interact with the annular groovesand cylindrical trunks of those distraction spacers in the same manneras described herein.

[0025] With regard to the dynamic trial described herein, the dynamictrial is provided primarily for distracting an intervertebral spaceaccording to the procedures described herein and/or for determining theappropriate size of an artificial intervertebral disc to be implanted(or whether a particular size can be implanted) into the distractedintervertebral space. While the distraction systems and methodsdescribed in the '127 application are also useful for distracting anintervertebral space, the dynamic trial is provided as an additional oralternate distraction tool. Further, while the static trials describedherein as useful for determining the appropriate size of an artificialintervertebral disc to be implanted (or whether a particular size can beimplanted), the dynamic trial is provided as an additional or alternatesizing tool.

[0026] The dynamic trial preferably includes a shaft having a bifurcatedtrial at a distal end. Each half of the bifurcated trial preferably hason its outwardly facing surface a convex dome that is shaped like theconvex dome of the corresponding baseplate of the artificialintervertebral disc that the dynamic trial approximates. The shaftincludes an inner shaft portion that centrally divides into upper andlower distal extensions that, from the point of division to their distalends, are each biased toward positions in which they converge toward oneanother. The lower distal extension is connected to the lower half ofthe bifurcated trial, and the upper distal extension is connected to theupper half of the bifurcated trial. Preferably, the upper half isadjustably connected to the upper distal extension by a pivot pin thatallows the upper half to rotate about a lateral axis that passes throughthe longitudinal and lateral center of the bifurcated trial. This axisof rotation allows the upper half, when separating from the lower half,to adjust to the orientation of the upper vertebral bone without causingthe bone to hinge relative to the lower vertebral bone. In order toeffect the separation of the upper and lower halves, the shaft furtherincludes an outer shaft potion that is translatable adjacent the innershaft portion, the outer shaft portion having a pin that passes betweenthe distal extensions.

[0027] The outer shaft portion is preferably translatable distally bythe forward movement of a control knob near the proximal end of theshaft, and translatable proximally by backward movement of the controlknob. As the outer shaft portion is pushed distally, the pin is pusheddistally to overcome the bias of the divided extensions to separate themand correspondingly separate the halves of the bifurcated trial.Preferably, markings are provided on the inner shaft portion to quantifythe depth (to which the bifurcated trial has been expanded)corresponding to the distance that the outer shaft portion has beentranslated with respect to the inner shaft portion. It is anticipatedthat the pushing force required to separate the halves will increase asthey separate, due to the compression of the spine seeking to close theintervertebral space and the annulus seeking to prevent the adjacentvertebral discs from separating beyond a certain point. Therefore, toprovide a mechanical advantage to the operator in the event that greaterdistraction is required, but the operator cannot push the control knobfarther with unaided human effort, an fine control knob is provided. Thefine control knob is preferably threaded onto the proximal end of theinner shaft portion, proximal to the control knob. Thus, rotation of thefine control knob about the longitudinal axis of the inner shaft portionwill cause the body of the fine control knob to press against thecontrol knob to move it farther distally. The interference of thethreads of the fine control knob-inner shaft portion interface preventsthe fine control knob from backing up proximally unless the fine controlknob is reverse rotated to effect that result. Finally, the proximal endof the shaft is preferably flanged to serve as a slap hammer forimpaction, if necessary for proper positioning of the bifurcated trial,and/or forced extraction of the bifurcated trial.

[0028] With further regard to the inserter/impactor described herein,the inserter/impactor is provided primarily for holding, inserting,repositioning, removing, impacting, extracting, and otherwisemanipulating an artificial intervertebral disc (or static trial) havingfeatures suitable for being manipulated by the inserter/impactor.Exemplary suitable artificial intervertebral discs are described in the'160 application with regard to FIGS. 8a-y, 9 a-t, 10 a-t, 11 a-j, and12 a-o thereof and by the accompanying descriptions therefor (e.g.,embodiments identified as the first, second, third, fourth, and fifthpreferred embodiments of the fourth embodiment family, etc.). Regardingthe features suitable for being manipulated by the inserter/impactor,such features include those discussed above as being suitable featureson the static trials and artificial intervertebral disc, namely, ananteriorly facing flat surface on the second (e.g., lower) baseplate ofthe trial or disc, flanked by two anteriolaterally facing flat surfaces(one on each side of the anteriorly facing flat surface), and, toprovide for holding of the trial or disc for an anterior insertionapproach, a hole spaced from the anteriorly facing flat surface, thehole having a longitudinal axis parallel to the anteriorly facing flatsurface.

[0029] The inserter/impactor includes a shaft having a distal end thathas angled flat surfaces corresponding to and fittable against theangled flat surfaces of the static trial or artificial intervertebraldisc, and a holding pin that extends from the center flat surface alonga longitudinal axis of the shaft, the pin having a distal end that bendsdownward. The holding pin is spring loaded in a central channel of theshaft, so that it is biased toward and against the central flat surface(preferably, the bent end of the pin prevents it from entering thecentral channel). A flange, mechanically connected to the pin andtranslating adjacent the shaft, can be pushed distally to overcome thebias of the spring to space the pin away from the central flat surface.In this position, the pin can be inserted in the hole in the baseplateof the artificial intervertebral disc. Releasing the knob allows thespring to pull the pin back, causing the anteriorly facing surface ofthe baseplate to be held against the central flat surface of theinserter/impactor and the anteriolaterally facing flat surfaces of theartificial intervertebral disc to be held against the othercorresponding flat surfaces of the inserter/impactor. A knob on theinserter/impactor can be rotated about the longitudinal axis of theshaft to pull the pin tighter and lock its position to more securelyhold the baseplate, and reverse rotated to unlock and loosen the pin.

[0030] When the static trial or artificial intervertebral disc is heldin this manner, rotation of the trial or disc about its longitudinalaxis relative to the inserter/impactor is prevented by interference ofthe corners of the trial's or disc's flat surfaces and the corners ofthe inserter/impactor's flat surfaces, similar to the manner in which awrench holding a nut prevents rotation of the nut relative to thewrench. Further, the holding of the trial or disc in this manner allowsfor some repositioning of the trial or disc in the intervertebral spacevia rotation of the trial or disc in either direction about thelongitudinal axis of the intervertebral space.

[0031] Preferably, both of the baseplates of the static trial or dischave similarly configured and oriented flat surfaces, and bothbaseplates' flat surfaces fit against the angled flat surfaces of theinserter/impactor, to provide for a more secure holding of the statictrial or disc by the inserter/impactor.

[0032] Also preferably, in order to provide for a holding of the statictrial or disc for two additional (here, anteriolateral) insertionapproaches, each static trial or disc also includes two additionalholes, one spaced apart from one of the anteriolaterally facing flatsurfaces, and the other spaced apart from the other of theanteriolaterally facing flat surfaces. Accordingly, operation of theinserter/impactor can fit the holding pin into either of these twoadditional holes, and hold the associated anteriolaterally facing flatsurface (the one associated with the hole into which the pin is fit) ofthe static trial or disc against the flat surface of theinserter/impactor opposite the pin. It should be understood thatpreferably, in order to facilitate these two additional approaches, theangle separating the anteriorly facing flat surface of the static trialor disc and one of the anteriolaterally facing flat surfaces of thestatic trial or disc is equal to the angle separating the anteriorlyfacing flat surface and the other of the anteriolaterally facing flatsurfaces.

[0033] Also preferably, as shown the baseplates of each of the pluralityof static trials are appropriately lordotically angled relative to oneanother to ease insertion of the static trial or artificialintervertebral disc into the intervertebral space and to mimic how theartificial intervertebral disc will typically be oriented as it is beinginserted.

[0034] With further regard to the repositioners/extractors describedherein, each repositioner/extractor is provided primarily forrepositioning and/or extracting a static trial or artificialintervertebral disc having features suitable for being manipulated bythe repositioner/extractor. Exemplary suitable artificial intervertebraldiscs are described in the '160 application with regard to FIGS. 8a-y, 9a-t, 10 a-t, 11 a-j, and 12 a-o thereof and by the accompanyingdescriptions therefor (e.g., embodiments identified as the first,second, third, fourth, and fifth preferred embodiments of the fourthembodiment family, etc.). Regarding the features suitable for beingmanipulated by each repositioner/extractor, such features include atleast two holes extending longitudinally into one of the baseplates ofthe static trial or artificial intervertebral disc from the inwardlyfacing surface of the baseplate. More than two holes can be used toprovide for multiple repositioning/extracting approaches. Preferably, inorder for the same repositioning/extracting tool to be used for multipleapproaches on the same trial or artificial intervertebral disc, adjacentholes should be separated by the same distance separating other adjacentholes.

[0035] In order to engage the two holes, each repositioner/extractor hastwo pins extending in parallel from a central shaft, perpendicular tothe longitudinal axis of the central shaft. The pins are spaced toengage the two holes simultaneously, and each pin has a diameter smallerthan the diameter of the hole it is to engage. Therefore, the pins canbe inserted into the holes, and pulling or pushing on the central shaftalong its longitudinal axis when the holes are engaged pulls or pushesthe static trial or artificial intervertebral disc in the intervertebralspace. Further, because two holes are engaged, the static trial orartificial intervertebral disc can be rotated in either direction abouta longitudinal axis passing through the intervertebral space, byrotating of the central shaft of the repositioner/extractor about itsdistal end, about an axis parallel to the longitudinal axes of the pins.A handle at a proximal end of the central shaft is useful for pushing orpulling on the shaft. A flange adjacent the proximal end of the shaft isuseful for impaction (either with a distally directed force or aproximally directed force), if necessary to manipulate the shaft.

[0036] On each repositioner/extractor, the pins are formed on prongsthat extend laterally from the central shaft. The direction of theprongs, and the location of the pins relative to the central shaft,determine the angle or angles of surgical approach for which aparticular repositioner/extractor can be used. Further, the number andlocation of holes further determine the angle or angles of surgicalapproach for which a particular repositioner/extractor can be used.Accordingly, the present invention contemplates a variety ofrepositioner/extractors, and a variety of holes configurations, toprovide the surgeon with a variety of possible surgical approach angles.

[0037] With further regard to the leveler described herein, the leveleris provided primarily for establishing a parallel orientation of thebaseplates (relative to one another), and/or securing the purchase ofthe stabilizing spikes, of an artificial intervertebral disc havingfeatures suitable for being manipulated by the leveler. Exemplarysuitable artificial intervertebral discs are described in the '160application with regard to FIGS. 8a-y, 9 a-t, 10 a-t, 11 a-j, and 12 a-othereof and by the accompanying descriptions therefor (e.g., embodimentsidentified as the first, second, third, fourth, and fifth preferredembodiments of the fourth embodiment family, etc.). Regarding thefeatures suitable for being manipulated by the leveler, such featuresinclude suitably formed inwardly facing surfaces of the baseplates ofthe artificial intervertebral disc.

[0038] More particularly, the leveler includes a shaft having a forkeddistal end formed by two opposing tongs that are symmetric to oneanother about a longitudinal axis of the shaft. Each of the tongs has anextent that initially curves laterally outward away from the shaft andfrom the other tong's extent, to define a central pocket forward of theshaft between the tongs' extents. Each tong's extent then resumes adistal direction to become parallel to the shaft and to the other tong'sextent.

[0039] Each tong's extent has an upper surface and a lower surface. Theupper surface is preferably shaped to conform against the inwardlyfacing surface of a first (e.g., upper) baseplate of an artificialintervertebral disc, and the lower surface is preferably shaped toconform against the inwardly facing surface of a second (e.g., lower)baseplate of the artificial intervertebral disc, so that insertion ofthe forked distal end of the leveler between the baseplates, with thecentral pocket of the distal end avoiding the central portion of theartificial intervertebral disc, and with the upper and lower surfaces soengaging the inwardly facing surfaces of the baseplates, causes thebaseplates to be placed in parallel orientation with respect to oneanother. A handle is provided at a proximal end of the shaft forpushing, pulling, and otherwise manipulating the leveler as needed.

[0040] When the artificial intervertebral disc is inserted into theintervertebral space, its baseplates will typically be lordoticallyangled with respect to one another. The leveler can be applied to theartificial intervertebral disc to bring the baseplates parallel to oneanother. The forked distal end of the leveler is inserted so that thetongs' extents are placed between the inwardly facing surfaces of thebaseplates, and so that the central pocket of the leveler avoids thatportion of the artificial intervertebral disc that joins the baseplates.As the leveler is inserted, the tongs act as wedges to force theposterior portions of the baseplates away from one another. Accordingly,as the posterior portions are being separated, the stabilizing spikes onthe outwardly facing surfaces of the baseplates find or secure theirpurchase in the hard bone of the outer ring of the vertebral bodyendplates. When the forked distal end is fully seated, the extents ofthe tongs hold the baseplates parallel to one another, and so that thespikes are fully engaged in the endplates.

BRIEF DESCRIPTION OF THE DRAWINGS

[0041]FIGS. 1a-f show front (FIG. 1a), side (FIG. 1b), perspective (FIG.1c), top (FIG. 1d), bottom cutaway (FIG. 1e) and top cutaway (FIG. 1f)views of a static trial of the present invention.

[0042]FIGS. 1g-n show front (FIG. 1g), side cutaway (FIG. 1h), top (FIG.1i), side cutaway (FIG. 1j), bottom cutaway (FIG. 1k), top cutaway (FIG.1l), bottom perspective (FIG. 1m), and top perspective (FIG. 1n) viewsof an exemplary artificial intervertebral disc of the present invention.

[0043]FIGS. 2a-k show top (FIG. 2a), side (FIG. 2b), perspective (FIG.2c), disassembly (FIG. 2d-j), and side cutaway (FIG. 2k) views of astatic trial holder of the present invention.

[0044]FIGS. 3a-d show side (FIG. 3a), top (FIG. 3b), side cutaway (FIG.3c), and perspective (FIG. 3d) views of a dynamic trial of the presentinvention.

[0045]FIGS. 4a-d show side (FIGS. 4a), top (FIG. 4b), side cutaway (FIG.4c), and perspective (FIG. 4d) views of an inserter/impactor of thepresent invention.

[0046]FIGS. 4e-h show side (FIG. 4e), top (FIG. 4f), side cutaway (FIG.4g), and perspective (FIG. 4h) views of an inserter/impactor of thepresent invention holding a static trial of the present invention.

[0047]FIGS. 4i-j. show top views of an inserter/impactor of the presentinvention holding a static trial of the present invention in twoalternative ways.

[0048]FIGS. 4k-n show side (FIG. 4k), top (FIG. 4l), side cutaway (FIG.4m), and perspective (FIG. 4n) views of an inserter/impactor of thepresent invention holding an exemplary artificial intervertebral disc ofthe present invention.

[0049]FIGS. 4o-p show top views of an inserter/impactor of the presentinvention holding an exemplary artificial intervertebral disc of thepresent invention in two alternative ways.

[0050]FIGS. 5a-c show side (FIG. 5a), top (FIG. 5b), and perspective(FIG. 5c) views of a symmetric repositioner/extractor of the presentinvention.

[0051]FIGS. 5d-f show side (FIG. 5d), top (FIG. 5e), and perspective(FIG. 5f) views of an offset left repositioner/extractor of the presentinvention.

[0052]FIGS. 5g-i show side (FIG. 5g), top (FIG. 5h), and perspective(FIG. 5i) views of an offset right repositioner/extractor of the presentinvention.

[0053]FIGS. 5j-l show side (FIG. 5j), top (FIG. 5k), and perspective(FIG. 5l) views of an alternative offset left repositioner/extractor ofthe present invention.

[0054]FIGS. 5m-o show side (FIG. 5m), top (FIG. 5n), and perspective(FIG. 5o) views of an alternative offset right repositioner/extractor ofthe present invention.

[0055]FIGS. 5p-u show exemplary various possible repositioner/extractorapproach angles with a three hole configuration of the presentinvention.

[0056]FIGS. 5v-dd show exemplary various possible repositioner/extractorapproach angles with a four hole configuration of the present invention.

[0057]FIGS. 6a-d bottom (FIG. 6a), side (FIG. 6b), front (FIG. 6c), toppartial perspective (FIG. 6d), and bottom partial perspective (FIG. 6e)views of a leveler of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0058] While the invention will be described more fully hereinafter withreference to the accompanying drawings, it is to be understood at theoutset that persons skilled in the art may modify the invention hereindescribed while achieving the functions and results of the invention.Accordingly, the descriptions that follow are to be understood asillustrative and exemplary of specific structures, aspects and featureswithin the broad scope of the invention and not as limiting of suchbroad scope. Like numbers refer to similar features of like elementsthroughout.

[0059] A preferred embodiment of a static trial of the presentinvention, and a preferred embodiment of an artificial intervertebraldisc of the present invention, both for use with the instrumentation ofthe present invention, will now be described.

[0060] Referring now to FIGS. 1a-f, a static trial of the presentinvention is shown in front (FIG. 1a), side (FIG. 1b), perspective (FIG.1c), top (FIG. 1d), bottom cutaway (FIG. 1e), and top cutaway (FIG. 1f)views. Referring now to FIGS. 1g-n, an artificial intervertebral disc ofthe present invention is shown in front (FIG. 1g), side cutaway (FIG.1h), top (FIG. 1i), side cutaway (FIG. 1j), bottom cutaway (FIG. 1k),top cutaway (FIG. 1l), bottom perspective (FIG. 1m), and top perspective(FIG. 1n) views.

[0061] It should be understood that the illustration and referenceherein to the artificial intervertebral disc shown in FIGS. 1g-n ismerely to show an example of one type of artificial intervertebral discthat is contemplated by, encompassed by, and suitable for use with, thepresent invention, and that such illustration and reference herein isnot meant to limit the scope of the present invention or limit the usesof the present invention. Rather, any other artificial intervertebraldisc (or any other orthopedic device) having suitable features for beingmanipulated by the instrumentation and methods described herein arecontemplated by the present invention. Indeed, the features suitable formanipulation (e.g., angled flat surfaces with adjacent holes) areencompassed by the present invention, regardless of to what orthopedicdevice they may be applied. Other exemplary suitable artificialintervertebral discs include, but are not limited to, the artificialintervertebral discs described in the '160 application with regard toFIGS. 8a-y, 9 a-t, 10 a-t, 11 a-j, and 12 a-o thereof and by theaccompanying descriptions therefor (e.g., embodiments identified as thefirst, second, third, fourth, and fifth preferred embodiments of thefourth embodiment family, etc.). It should be noted that, as can be seenfrom FIGS. 1g-n, that the artificial intervertebral disc shown in FIGS.1 g-n has features similar to those of these other suitable artificialintervertebral discs of the '160 application, and it should beunderstood that such similar features are structurally and functionallyas described in the '160 application. Such similar features include aninwardly facing surface 164 a of the upper baseplate 164 a, and a convexstructure 162 on the lower baseplate 168 b, the convex structure 162having an inwardly facing surface 164 b.

[0062] And, while the instrumentation described herein (e.g., the statictrials, static trial holder, dynamic trial, inserter/impactor,repositioners/extractors, and leveler) will be discussed for use withthe artificial intervertebral disc of FIGS. 1g-n, such discussions aremerely by way of example and not intended to be limiting of their uses.Thus, it should be understood that the tools can be used with any of theartificial intervertebral discs disclosed in the '160 application, orany other artificial intervertebral disc having (or being modifiable ormodified to have) suitable features therefor. Moreover, it isanticipated that the features of the artificial intervertebral disc(e.g., the flat surfaces and accompanying holes) and/or the statictrials (e.g., the cylindrical trunks and flat surfaces and accompanyingholes) that are used by the tools discussed herein to hold and/ormanipulate these devices (such features, it should be noted, were firstshown and disclosed in the '160 application and the '127 application)can be applied, individually or collectively or in various combinations,to other trials, spacers, artificial intervertebral discs or otherorthopedic devices as stand-alone innovative features for enabling suchtrials, spacers, artificial intervertebral discs, or other orthopedicdevices to be more efficiently and more effectively held and/ormanipulated by the tools described herein or by other tools havingsuitable features. In addition, it should be understood that theinvention encompasses artificial intervertebral discs, spacers, trials(static or dynamic), and/or other orthopedic devices, that have one ormore of the features disclosed herein, in any combination, and that theinvention is therefore not limited to artificial intervertebral discs,spacers, trials, and/or other orthopedic devices having all of thefeatures simultaneously.

[0063] A plurality of static trials 100 are provided primarily for usein determining the appropriate size of an artificial intervertebral discto be implanted (or whether a particular size of the artificialintervertebral disc can be implanted) into the distracted intervertebralspace (e.g., the artificial intervertebral disc 160 of FIGS. 1g-n).Preferably, for each artificial intervertebral disc to be implanted, aplurality of sizes of the artificial intervertebral disc would beavailable. That is, preferably, a plurality of the same type ofartificial intervertebral disc would be available, each of the pluralityhaving a respective width and depth dimension combination that allows itto fit within a correspondingly dimensioned intervertebral space. Forexample, the plurality of artificial intervertebral discs could includeartificial intervertebral discs having widths being either 35 mm or 40mm, and depths ranging from 14 mm to 18 mm in 1 mm increments, for atotal of 10 discs. Accordingly, preferably, each of the plurality ofstatic trials 100 for use with a particular plurality of differentlysized artificial intervertebral discs would have a respective width anddepth dimension set corresponding to the width and depth of a respectiveone of the plurality of differently sized artificial intervertebraldiscs. For example, the plurality of static trials 100 for use with theset of artificial intervertebral discs described for example couldinclude static trials 100 having widths being either 35 mm or 40 mm, anddepths ranging from 14 mm to 18 mm in 1 mm increments, for a total of 10static trials. It should be understood that the artificialintervertebral discs and/or the static trials 100 can be offered in avariety of dimensions without departing from the scope of the invention,and that the dimensions specifically identified and quantified hereinare merely exemplary. Moreover, it should be understood that the set ofstatic trials 100 need not include the same number of trials for eachartificial intervertebral disc in the set of artificial intervertebraldiscs, but rather, none, one, or more than one trial can be included inthe trial set for any particular artificial intervertebral disc in theset.

[0064] Each of the static trials (the static trial 100 shown isexemplary for all of the static trials in the plurality of statictrials; preferably the static trials in the plurality differ from oneanother only with regard to overall dimensions as described above)includes at least one feature that can be gripped by a tool. Suitabletools include, but are not limited to, the static trial holder 200described below, the inserter/impactor 400 described below, and therepositioners/extractors 510, 520, 530, 540 described below.Specifically, the static trial 100 includes a recess 102 that can begripped by the opposing semicircular extents 216 a-b of the static trialholder 200. Preferably, this recess 102 forms an annular groove 104 thatestablishes a cylindrical trunk 106 between the upper and lowerbaseplates 108 a-b of the static trial 100, such that the baseplates 108a-b extend as flanges 110 a-b from either end of the cylindrical trunk106. Accordingly, preferably, the opposing semicircular extents 216 a-beach have a thickness smaller than the width of the annular groove 104,and as such fit into the annular groove 104 to grip the cylindricaltrunk 106 between them.

[0065] In some embodiments, while not shown in FIGS. 1a-f, it is alsopreferable that the annular groove 104 radially widen outwardly, suchthat the walls 112 of the annular groove 104 are tapered toward oneanother with the increasing depth of the groove 104, such that the floor114 of the groove 104 is more narrow than the opening 116 of the groove104. Accordingly, preferably, in such embodiments, each semicircularextent 216 a-b correspondingly radially widens outwardly, such that thethinner portion of the extent 216 a-b fits closer to the floor 114 ofthe annular groove 104, so that the tapered surfaces of the extents 216a-b compress against the tapered walls 112 of the annular groove 104when the static trial 100 is gripped by the static trial holder 200.This taper locking provides for a secure grip so that the static trial100 can be manipulated accurately and efficiently.

[0066] In some embodiments, while not shown in FIGS. 1a-f, it is alsopreferable that the floor of the annular groove 104 of the cylindricaltrunk 106 be ridged (e.g., have ridges that run parallel to thelongitudinal axis of the cylindrical trunk), and the surfaces of thesemicircular extents 216 a-b of the static trial holder 200 thatcompress against the floor of the annular groove 104 when the statictrial holder 200 grips the static trial 100 be correspondingly providedwith ridges. The interlocking of the ridges of the static trial 100 withthe ridges of the static trial holder 200 when the static trial 100 isgripped prevents rotation of the static trial 100 about the longitudinalaxis of the cylindrical trunk 106 with respect to the static trialholder 200.

[0067] Additionally with regard to features that can be gripped by atool, each of the static trials includes at least one feature that canbe gripped by a tool that preferably is also used to grip the artificialintervertebral disc that the trial approximates. Suitable tools that cangrip both the trial and the artificial intervertebral disc include, butare not limited to, the inserter/impactor 400 described below.Specifically, for being gripped by the inserter/impactor 400, eachstatic trial 100 and artificial intervertebral disc 160 includes ananteriorly facing flat surface 120 b, 180 b, flanked by twoanteriolaterally facing flat surfaces 120 a,180 a and 120 c,180 c (oneon each side of the anteriorly facing flat surface 120 b,180 b), and, toprovide for holding of the static trial 100 or disc 160 for an anteriorinsertion approach, a hole 122 b,182 b spaced from the anteriorly facingflat surface, the hole 122 b,182 b having a longitudinal axis parallelto the anteriorly facing flat surface 120 b,180 b.

[0068] The holding pin 408 of the inserter/impactor 400 fits within thehole 122 b,182 b, and the angled flat surfaces 120 a-c,180 a-c of thestatic trial 100 or disc 160 fit against the correspondingly angled flatsurfaces 420 a-c of the inserter/impactor 400, and operation of theinserter/impactor 400 pulls the holding pin 408 toward the flat surface120 b,180 b of the inserter/impactor 400 opposite the pin 408, torigidly hold the static trial 100 or disc 160 by the structure of thestatic trial 100 or disc 160 having the hole 122 b,182 b (e.g., thebaseplate 108 b,168 b). When the static trial 100 or disc 160 is held inthis manner, rotation of the static trial 100 or disc 160 about alongitudinal axis (of the static trial 100 or disc 160) relative to theinserter/impactor 400 is prevented by interference of the corners of thestatic trial's 100 or disc's 160 flat surfaces 120 a-c,180 a-c and thecorners of the inserter/impactor's 400 flat surfaces 420 a-c, similar tothe manner in which a wrench holding a nut prevents rotation of the nutrelative to the wrench. Further, the holding of the static trial 100 ordisc 160 in this manner allows for some repositioning of the statictrial 100 or disc 160 in the intervertebral space via rotation of thestatic trial 100 or disc 160 in either direction about the longitudinalaxis of the intervertebral space.

[0069] Preferably, both of the baseplates of the static trial 100 ordisc 160 have similarly configured flat surfaces. For example, the lowerbaseplate's 108 b,168 b flat surfaces 120 a-c,180 a-c have similarlyconfigured and similarly oriented counterpart flat surfaces 120 d-f, 180d-f on the upper baseplate 108 a, 168 a. Further preferably, bothbaseplates' 108 a-b,168 a-b flat surfaces 120 a-f,180 a-f face theangled flat surfaces 420 a-c of the inserter/impactor 400 when thestatic trial 100 or disc 160 is held by the inserter/impactor 400. Forexample, as discussed below with regard to the inserter/impactor 400, inan anterior approach for the trial 100 (as shown in FIGS. 4e-h), 120 aand 120 d facing 420 a,120 b and 120 e facing 420 b, and 120 c and 120 ffacing 420 c, and in an anterior approach for the disc 160 (as shown inFIGS. 4k-n), 180 a and 180 d facing 420 a, 180 b and 180 e facing 420 b,and 180 c and 180 f facing 420 c.

[0070] It should be noted that preferably, when the static trial 100 isheld by the inserter/impactor 400, the flat surfaces 120 a-c and thecounterpart flat surfaces 120 d-f are tightly held against the angledflat surfaces 420 a-c of the inserter/impactor 400 as described above.It is also preferable that the baseplates 108 a-b of each of theplurality of static trials 100 be appropriately lordotically angledrelative to one another to ease insertion of the static trial 100 intothe intervertebral space and to mimic how the artificial intervertebraldisc 160 will typically be oriented as it is being inserted using theinserter/impactor 400, and to ease insertion of the static trial 100into the intervertebral space. While not shown in FIGS. 1a-f, in someembodiments, when the static trials 100 are formed in such alordotically oriented configuration, it is preferable that the flatsurfaces 120 d-f on the first (e.g., upper) baseplate 108 a be parallelto the flat surfaces 120 a-c of the second (e.g., lower) baseplate 108 bin the static trial's 100 appropriately lordotically orientedconfiguration, so that when the static trial 100 is held tightly by theinserter/impactor 400, the flat surfaces 120 a-f are flush with the flatsurfaces 420 a-c of the inserter/impactor 400 even though the baseplates108 a-b are lordotically angled with respect to one another.

[0071] By contrast, preferably, when the artificial intervertebral disc160 is held by the inserter/impactor 400, the flat surfaces 180 a-c aretightly held against the angled flat surfaces 420 a-c of theinserter/impactor 400 as described above, but the counterpart flatsurfaces 180 d-f are loosely held against the angled flat surfaces 420a-c of the inserter/impactor 400. As such, the structure of theartificial intervertebral disc 160 having the counterpart flat surfaces180 d-f (e.g., the upper baseplate 168 a) is able to angulate and rotateto a limited extent relative to the structure of the artificialintervertebral disc 160 having the flat surfaces 180 a-c. This permitsthe artificial intervertebral disc 160 to adjust to the intervertebralspace (e.g., to the angulation of the adjacent vertebral endplates,defining the intervertebral space, relative to one another) as it isbeing inserted thereinto. That is, typically, the adjacent vertebralendplates will be lordotically angled with respect to one another as aresult of the intervertebral space being prepared and distracted. As theartificial intervertebral disc 160 is then inserted into theintervertebral space using the inserter/impactor 400, then, thebaseplates 168 a-b will be permitted to lordotically angle with respectto one another to squeeze into the intervertebral space.

[0072] Also preferably, in order to provide for a holding of the statictrial 100 or disc 160 for two additional (here, anteriolateral)insertion approaches, each static trial 100 or disc 160 also includestwo additional holes 122 a,182 a and 122 c,182 c, one (e.g., 122 a,182a) spaced apart from one of the anteriolaterally facing flat surfaces(e.g., 120 a,180 a), and the other (e.g., 122 c,182 c) spaced apart fromthe other of the anteriolaterally facing flat surfaces (e.g., 120 c,180c). Accordingly, operation of the inserter/impactor 400 can fit theholding pin 408 into either of these two additional holes 122 a,182 a or122 c,182 c, and hold the associated anteriolaterally facing flatsurface (the one associated with the hole into which the pin 408 is fit)of the static trial 100 or disc 160 against the flat surface of theinserter/impactor 400 opposite the pin 408. For example, as discussedbelow with regard to the inserter/impactor 400, in a firstanteriolateral approach for the trial 100 (as shown in FIG. 4i), 120 aand 120 d facing 420 b, 120 b and 120 e not confronted, and 120 c and120 f facing 420 a, and a first anteriolateral approach for the disc 160(as shown in FIG. 4o), 180 a and 180 d facing 420 b, 180 b and 180 e notconfronted, 180 c and 180 f facing 420 a. And, for example, as discussedbelow with regard to the inserter/impactor 400, in a secondanteriolateral approach for the trial 100 (as shown in FIG. 4j), 120 aand 120 d facing 420 c, 120 b and 120 e facing 420 a, and 120 c and 120f not confronted, and a second anteriolateral approach for the disc 160(as shown in FIG. 4p), 180 a and 180 d facing 420 c, 180 b and 180 efacing 420 a, 180 c and 180 f not confronted.

[0073] It should be understood that preferably, in order to facilitatethese additional approaches, the angle separating the anteriorly facingflat surface of the static trial 100 or disc 160 and one of theanteriolaterally facing flat surfaces of the static trial 100 or disc160 is equal to the angle separating the anteriorly facing flat surfaceand the other of the anteriolaterally facing flat surfaces. Preferably,the surfaces are angled with respect to one another at an angle of 33.4degrees.

[0074] It should also be understood that the inclusion of additionaladjacent angulated surfaces (or placing the angulated surfaces in otherlocations on the trial or disc), and/or including corresponding holesadjacent to such surfaces, can provide the surgeon with additionalapproaches, e.g., other anteriolateral approaches, directly lateralapproaches, posteriolateral approaches, and/or directly posteriorapproaches. For example, a trial or disc can have angled surfaces (andcorresponding holes) along the entire perimeter of one or both of thebaseplates, and thus enable the surgeon to engage the trial or disc froma number of angles, including anterior, posterior, lateral,anteriolateral, and posteriolateral angles.

[0075] Additionally with regard to features that can be gripped by atool, each of the static trials includes at least one feature that canbe gripped by a tool that preferably is also used to grip the artificialintervertebral disc that the trial approximates. Suitable tools that cangrip both the trial and the artificial intervertebral disc include, butare not limited to, the repositioners/extractors 500, 510, 520, 530, 540described below. Specifically, for being gripped by therepositioners/extractors, each static trial 100 and artificialintervertebral disc 160 includes at least two holes extendinglongitudinally into one of the baseplates of the static trial 100 orartificial intervertebral disc 160 from the inwardly facing surface ofthe baseplate. More than two holes can be used to provide for multiplerepositioning/extracting approaches. Preferably, in order for the samerepositioning/extracting tool to be used for multiple approaches on thesame trial or artificial intervertebral disc, adjacent holes should beseparated by the same distance separating other adjacent holes.

[0076] As discussed in greater detail below with regard to therepositioners/extractors 500, 510, 520, 530, 540, in order to engage twoof the holes, each repositioner/extractor has two pins extending inparallel from a central shaft, perpendicular to the longitudinal axis ofthe central shaft. The pins are spaced to engage the two holessimultaneously, and each pin has a diameter smaller than the diameter ofthe hole it is to engage. Therefore, the pins can be inserted into theholes, and pulling or pushing on the central shaft along itslongitudinal axis when the holes are engaged pulls or pushes the statictrial or artificial intervertebral disc in the intervertebral space.Further, because two holes are engaged, the static trial or artificialintervertebral disc can be rotated in either direction about alongitudinal axis passing through the intervertebral space, by rotatingof the central shaft of the repositioner/extractor about its distal end,about an axis parallel to the longitudinal axes of the pins. A handle ata proximal end of the central shaft is useful for pushing or pulling onthe shaft. A flange adjacent the proximal end of the shaft is useful forimpaction (either with a distally directed force or a proximallydirected force), if necessary to manipulate the shaft.

[0077] On each repositioner/extractor, the pins are formed on prongsthat extend laterally from the central shaft. The direction of theprongs, and the location of the pins relative to the central shaft,determine the angle or angles of surgical approach for which aparticular repositioner/extractor can be used. Further, the number andlocation of holes further determine the angle or angles of surgicalapproach for which a particular repositioner/extractor can be used.Accordingly, the present invention contemplates a variety ofrepositioner/extractors, and a variety of holes configurations, toprovide the surgeon with a variety of possible surgical approach angles.

[0078] As described in greater detail below, threerepositioner/extractors are illustrated and described (symmetric, offsetleft, and offset right) for example, and, for example, two holeconfigurations are illustrated and described. Referring again to FIGS.1a-n, a first hole configuration includes the hole configurationdescribed above, that is, three holes on one of the baseplates (e.g.,the lower baseplate 108 b,168 b), the holes being configured so that afirst hole 122 b,182 b is located in the anterior-posterior plane, andthe adjacent (second 122 a,182 a and third 122 c,182 c) holes arelocated in respective opposing anteriolateral planes on either side ofthe first hole 122 b,182 b. (This hole configuration is also shown inFIGS. 5p-u, each of which shows a top cutaway view of the artificialintervertebral disc 160 of FIGS. 1g-n, showing its lower baseplate 168b, having the first hole configuration, engaged by one of therepositioners/extractors 500,510,520. Each view of the lower baseplate168 b shows the first hole 182 b, the second hole 182 a, and the thirdhole 182 c of the first hole configuration.)

[0079] Referring again to FIGS. 1a-n, a second hole configurationincludes four holes on one of the baseplates (e.g., the upper baseplate108 a,168 a), the holes being configured so that first (e.g., 130 c,190c) and second (e.g., 130 b,190 b) holes straddle the anterior-posteriorplane, a third hole (e.g., 130 d,190 d) is located so that the thirdhole and the first hole straddle one of the opposing anteriolateralplanes, and a fourth hole (e.g., 130 a,190 a) is located so that thefourth hole and the second hole straddle the other of the opposinganteriolateral planes. (This hole configuration is also shown in FIGS.5v-dd, each of which shows a bottom cutaway view of the artificialintervertebral disc of FIGS. 1g-n, showing its upper baseplate 168 a,having the second hole configuration, engaged by one of therepositioners/extractors 500,510,520. Each view of the upper baseplateshows the first hole 190 c, the second hole 190 b, the third hole 190 d,and the fourth hole 190 a, of the second hole configuration.)

[0080] It should be understood that configurations having more or fewerholes, and in a variety of locations, are contemplated by the invention,and the detailed descriptions of only two hole configurations is notmeant to limit the invention to only these two configurations.Importantly, the invention encompasses using a hole or any number ofholes, bored at any suitable angle, whether parallel to other holes ornot, in any number of locations on a spacer, a trial or an artificialintervertebral disc (not limited to locations on the baseplates), forpurposes of enabling the spacer, trial, or disc to be gripped by amanipulation instrument (not limited to a repositioner/extractor) thatengages the hole, and/or to enable the surgeon to work from a variety ofapproaches. For example, as described in more detail below, the firstand second hole configurations described herein, in cooperation with therepositioner/extractors, provide the surgeon with the ability to workfrom a directly anterior approach, as well as several anteriolateralapproaches. It should be understood that additional hole configurationscan enable the surgeon to work from a directly posterior approach,posteriolateral approaches, directly lateral approaches, oranteriolateral approaches that are different that those illustrated. Forexample, the placement of one or more suitably spaced holes (or theaddition of one or more holes) on the posterior edge, and/or one or bothof the lateral edges of one or both of the baseplates, would enable thesurgeon to use the repositioner/extractors of the present invention toachieve such approaches.

[0081] Thus, it can be seen that each of the repositioner/extractors canbe used in more than one manner depending on the tool desired and theapproach desired. These manners are described in greater detail belowand illustrated in FIGS. 5p-dd with regard to the detailed descriptionof the repositioners/extractors.

[0082] Also preferably, the baseplates 108 a-b of each of the pluralityof static trials 100 preferably has a convex dome 124 a-b on itsoutwardly facing surface 126 a-b that is shaped like the convex dome 184a-b on the outwardly facing surface 186 a-b of the correspondingbaseplate 168 a-b of the artificial intervertebral disc 160 that thestatic trial 100 approximates. Preferably, each convex dome 124 a-b issmooth, rather than having a porous coating that is preferred for theconvex domes 184 a-b of the artificial intervertebral disc 160, and eachoutwardly facing surface 126 a-b does not have stabilizing spikes suchas the stabilizing spikes 188 a-b on the outwardly facing surfaces 186a-b of the artificial intervertebral disc 160. The omission of thesedevice stabilizing and bone ingrowth encouraging structures and surfaceson the static trials 100 enables the surgeon to test the size of theartificial intervertebral disc 160 to be implanted without traumaticallyengaging the vertebral body endplates.

[0083] Accordingly, the surgeon can prepare and distract theintervertebral space, and then insert and remove at least one of thestatic trials (or more, as necessary) to find the size that is mostappropriate for the intervertebral space.

[0084] A preferred embodiment of a static trial holder of the presentinvention will now be described.

[0085] Referring to FIGS. 2a-c and 2 k, a static trial holder of thepresent invention is shown in side (FIG. 2a), top (FIG. 2b), perspective(FIG. 2c), and side cutaway (FIG. 2k) views. In addition, referring toFIGS. 2d-f, a sleeve of the static trial holder is shown in side cutaway(FIG. 2d), front (FIG. 2e), and back (with partial cutaway) (FIG. 2views. In addition, referring to FIGS. 2g-i, an extension of the statictrial holder is shown in top (FIG. 2g), proximal cutaway (FIG. 2h), side(FIG. 2i), and distal cutaway (FIG. 2j) views.

[0086] The static trial holder 200 is provided primarily for use inholding, inserting and removing the static trials described herein, ordistraction spacers having suitable features therefor, such as thedistraction spacers disclosed in the '127 application.

[0087] More specifically, the static trial holder 200 includes a handle202, an extension 204, and a sleeve 206. As shown in FIG. 2k, the handle202 and the extension 204 are fixed to one another (preferably by thedistal end of the handle 202 being fixed to the proximal end of theextension 204) to form a shaft 208. The sleeve 206 surrounds theextension 204 and is rotatable with respect to the handle 202 and theextension 204 about the longitudinal axis of the shaft 208. The handle202 preferably has an flange 232 at its proximal end for use in applyinga distally or proximally directed force to get the static trial 100 (ordistraction spacer) into or out of the intervertebral space, and/or foruse in helping the surgeon rotate the sleeve 206 with respect to theextension 204 (by gripping the flange 232 and the control knob 219described below).

[0088] The distal end of the extension 204 forms a contractable andexpandable holding enclosure 210 in that the distal end is divided at afulcrum 212 into two prongs 214 a-b, each of which terminates in asemicircular extent 216 a-b, each of which has a tapered end 215 a-b.The extents 216 a-b are oriented such that the tapered ends 215 a-b faceone another to define a radially inwardly tapering mouth 213, and suchthat the semicircular openings oppose one another to define the holdingenclosure 210. The prongs 214 a-b are spring biased toward a neutralposition (preferably by the formation of the fulcrum 212 in combinationwith the strength of the material of which the extension 204 is made)such that the holding enclosure 210 is spring biased to a receptivestate (described below), but the prongs 214 a-b can be brought togetherto contract the holding enclosure 210 to a contracted state, (describedbelow) or the prongs 214 a-b can be further separated to expand theholding enclosure 210 to an expanded state (described below).

[0089] When the holding enclosure 210 is in the receptive state, thewidth of the mouth 213 of the holding enclosure 210 does not accommodatethe diameter of the cylindrical trunk 106 of the static trial 100 (ordistraction spacer) for passage therethrough. However, from thisreceptive state, the mouth 213 can be temporarily widened (placing theholding enclosure 210 in its expanded state) to accommodate the diameter(for passage of the cylindrical trunk 106 through the mouth 213), if asufficient force is applied to overcome the neutral position bias of theprongs 214 a-b and thus widen the mouth 213. (Preferably, there isenough space between the outer surfaces of the prongs 214 a-b and theinner surface of the bore 218 of the sleeve, when the prongs 214 a-b arein their neutral position, so that the prongs 214 a-b can be separatedwithout interference.) The sufficient force can be applied by pressingthe cylindrical trunk 106 against the tapered ends 215 a-b of the mouth213, in that the separating force component of the radially inward forceof the pressing will be applied to the semicircular extents 216 a-b bythe taper of the tapered ends 215 a-b. Because the holding enclosure 210is biased toward the receptive state, after the cylindrical trunk 106 ispassed through the mouth 213 and into the holding enclosure 210, theholding enclosure 210 will return to its receptive state in which thewidth of the mouth 213 does not allow passage of the cylindrical trunk106 without the sufficient force. Preferably, the force required towiden the mouth 213 is greater than gravity and/or the greatest forcethat will be experienced by moving the static trial holder 200 prior toplacing the holding enclosure 210 in the contracted state. Therefore,once the cylindrical trunk 106 is in the holding enclosure 210, evenbefore the holding enclosure 210 is placed in its contracted state, thecylindrical trunk 106 will not escape the holding enclosure 210 as thestatic trial holder 200 is oriented with the holding enclosure 210downward, or is moved about.

[0090] It should be understood that when the static trial 100 (ordistraction spacer) is being held (either when the holding enclosure 210is in its receptive state or in its contracted state discussed below),because the semicylindrical extents 216 a-b fit within the annulargroove 104 of the static trial 100 (or distraction spacer), the statictrial 100 (or distraction spacer) will not escape from the enclosurealong the longitudinal axis of the cylindrical trunk 106. That is, asnoted above, the recess 102 of each static trial 100 (or distractionspacer) forms an annular groove 104 that establishes the cylindricaltrunk 106 between the baseplates of the static trial (or distractionspacer), such that the baseplates extend as flanges from either end ofthe cylindrical trunk 106. Accordingly, preferably, the opposingsemicircular extents each have a thickness smaller than the width of theannular groove 104, and as such fit into the annular groove 104 to gripthe cylindrical trunk 106 between them.

[0091] In some embodiments, while not shown in FIGS. 1a-f or FIGS. 2a-k,it is preferable that the annular groove 104 radially widen outwardly,such that the walls of the annular groove 104 taper toward one anotherwith the increasing depth of the groove, such that the floor of thegroove is more narrow than the opening 116 of the groove. Accordingly,preferably, in such embodiments, each semicircular extent 216 a-bcorrespondingly radially widens outwardly, such that the thinner portionof the extent 216 a-b fits closer to the floor of the annular groove104, so that the tapered surfaces 215 a-b of the extents 216 a-bcompress against the tapered walls of the annular groove 104 when thestatic trial 100 is gripped by the static trial holder 200. This taperlocking provides for a secure grip so that the static trial 100 can bemanipulated accurately and efficiently.

[0092] In some embodiments, while not shown in FIGS. 1a-f or FIGS. 2a-k,it is also preferable that the floor of the annular groove 104 of thecylindrical trunk 106 be ridged (e.g., have ridges that run parallel tothe longitudinal axis of the cylindrical trunk), and the surfaces of thesemicircular extents 216 a-b of the static trial holder 200 thatcompress against the floor of the annular groove 104 when the statictrial holder 200 grips the static trial 100 be correspondingly providedwith ridges. The interlocking of the ridges of the static trial 100 withthe ridges of the static trial holder 200 when the static trial 100 isgripped prevents rotation of the static trial 100 about the longitudinalaxis of the cylindrical trunk 106 with respect to the static trialholder 200.

[0093] In order to more tightly hold the static trial 100 (ordistraction spacer) for manipulation of the static trial 100 (ordistraction spacer) during surgical procedures in which greater forceswill be experienced by the static trial 100 (or distraction spacer) andthe static trial holder 200, the holding enclosure 210 can be placed ina contracted state. The holding enclosure 210 can be considered“unlocked” in its receptive or expanded states, and “locked” in itscontracted state, with respect to the nature of the hold that the statictrial holder 200 potentially can have or has on the cylindrical trunk106. Preferably, when the holding enclosure 210 is locked, a forcegreater than that which is applicable by an unaided surgeon or nurse(i.e., that which can be applied to remove the cylindrical trunk 106from the holding enclosure 210 when the holding enclosure 210 is in itsreceptive state), and greater than that which will be experienced by thestatic trial 100 (or distraction spacer) and the static trial holder 200during surgical procedures) would be required to pull the cylindricaltrunk 106 out of the holding enclosure 210. The placement of the holdingenclosure 210 in its locked state or unlocked state is effected byoperation of a holding assembly that includes the extension 204 and thesleeve 206 and the manner in which they are configured and interact.

[0094] More particularly, the prongs 214 a-b can be brought together, tolock the holding enclosure 210, by a rotation of the sleeve 206 withrespect to the handle 202 and the extension 204 about the longitudinalaxis of the shaft 208. A rotation control knob 219 is provided to easethe rotation of the sleeve 206. As shown in FIGS. 2g and 2 i-j in viewof FIGS. 2d-e, the bore 218 of the sleeve 206 (shown in cutaway in FIG.2e) defines a cross-section that has a width 220 that is greater thanits depth 222. Further as shown in those figures, the prongs 214 a-bwhen separated (shown in cutaway in FIG. 2j) define a cross-sectionhaving a width 224 that is greater than its depth 226, the width 224 anddepth 226 of the prong' cross-section being closely accommodated by thewidth 220 and depth 222 of the bore's cross-section. When the prongs 214a-b are together, the width of prongs' cross-section is closelyaccommodated by the depth 222 of the bore's cross-section. Thus, whenthe sleeve 206 is rotated with respect to the extension 204, the sidesof the bore defining the depth 222 of its cross-section bear against thesides of the prongs 214 a-b defining the width of their cross-section.

[0095] It should be noted that in order to ease the rotation of thesleeve 210 so that the side of the bore 218 can bear against the sidesof the prongs 214 a-b, the corners of the bore 218 are radiused, and atleast the sides (that face away from one another) of the prongs 214 a-bare curved. Preferably, as shown, the prongs 214 a-b when separateddefine a partial cylindrical cross-section. The effect of the bearing(of the sides of the bore 218 against the sides of the prongs 214 a-b)is borne by the space between the prongs 214 a-b, so that the spacenarrows and the prongs 214 a-b are brought toward one another until theyare accommodated within the bore's depth 222. The bringing together ofthe prongs 214 a-b brings the semicircular extents 216 a-b together toplace the holding enclosure 210 into its contracted state, locking it.

[0096] Preferably, the sleeve 206 is biased toward establishing theholding enclosure 210 in either an unlocked position or a lockedposition. Stated alternatively, when the holding enclosure 210 isunlocked (or locked), the force required to begin rotation of the sleeve206 is greater than the force required to continue rotating the sleeve206 once rotation has begun. And, as the sleeve 206 is rotated toward aposition that will unlock (or lock), the holding enclosure 210, it isbiased toward stopping its rotation at that upcoming position. Statedalternatively, as the sleeve 206 is being rotated, the force required torotate the sleeve 206 past that upcoming position is greater than theforce that is required to rotate it prior to reaching that upcomingposition.

[0097] This biasing of the sleeve 206 toward positions that will eitherunlock or lock the holding enclosure 210 is effected by the inclusion ofat least one spaced recess 228 on the outer surface of the extension204, and at least one radial bore 230 through the wall of the sleeve 206(preferably through the rotation control knob 219 as shown), which bores230 each have secured therein a spring plunger (not shown) (it should beunderstood that functionally equivalent devices can also be used inplace of a spring plunger). Preferably, each recess 228 is associatedwith a respective cooperating bore 230 and spring plunger. When a givenbore 230 (and spring plunger) is aligned with its associated recess 228,the sleeve 206 is in a position at which the holding enclosure 210 iseither unlocked or locked. Each of the spring plungers is biasedradially inwardly from the inner surface of the sleeve 206, and as suchpresses against the outer surface of the extension 204 as the sleeve 206is being rotated. Thus, when a recess 230 is presented to the springplunger, it plunges into the recess 230, stopping the rotation of thesleeve 206. In order to restart (or continue) rotation of the sleeve206, the bias of the spring plunger must be overcome when the restarting(or continuing) rotational force is applied. In order to lower theovercoming force required to restart or continue the rotation, the endof the spring plunger is preferably convexly curvate, and the recess isconcavely curvate. Preferably, four recesses 228 and bores 230 (andspring plungers) are provided, each pair representing one of fourquarter-turn rotated positions of the sleeve 206. At each position ofthe sleeve 206, all four plungers plunge into the recesses 228, securingthe sleeve 206 at that position until a sufficient force is applied toovercome their plunging bias.

[0098] Accordingly, the static trials 100 of the invention (ordistraction spacers such as those disclosed in the '127 application) canbe held and manipulated with the static trial holder 200. Holding thehandle 202 of the static trial holder 200 in one hand, an operator canpush the cylindrical trunk 106 of the static trial 100 (or thedistraction spacer) against the mouth 213 of the holding enclosure 210with enough force to temporarily expand the mouth 213 to a width thatwill accommodate the diameter of the cylindrical trunk 106 for passagethrough the mouth 213. The radially inward tapering of the sides of themouth 213 (the facing ends 215 a-b of the semicircular extents 216 a-bof the prongs 214 a-b) facilitates this insertion. Once the cylindricaltrunk 106 has passed into the holding enclosure 210, the operator canlet go of the static trial 100 (or distraction spacer) because theprongs 214 a-b will be overcome by their bias toward their neutral stateand thus hold the static trial 100 in the holding enclosure 210 toprevent the static trial 100 from falling out or slipping out as thestatic trial holder 200 is moved with the static trial 100 prior toclosing (e.g., locking) the holding enclosure 210. (When the statictrial 100 (or distraction spacer) is being held in this manner, and theholding enclosure 210 is unlocked, the static trial 100 can be removedfrom the holding enclosure 210 by a pulling of the static trial 100through the mouth 213 of the holding enclosure 210 with a force requiredto again temporarily overcome the bias of the prongs 214 a-b towardtheir neutral state, to separate them and make the width of the mouth213 accommodate the diameter of the cylindrical trunk 106.)

[0099] Once the operator is ready to lock the holding enclosure 210,while still gripping the handle 202 of the static trial holder 200, herotates the rotation control knob 219 either clockwise orcounterclockwise to move the sleeve 206 to the next quarter-turnposition. If the rotation control knob 219 is rotated with enough forceto cause the spring plungers in the bores 230 to back out of therecesses 228, the sleeve 206 will rotate as desired. Once the sleeve 206has reached the next quarter-turn position, the spring plungers willfind the recesses 228 associated with that position, and plunge into therecesses 228 to snap the sleeve 206 into the proper position. As thesleeve 206 rotates, the sides of the sleeve's bore's inner surface bearagainst the curved outer surfaces of the prongs 214 a-b to push theprongs 214 a-b together so that they are accommodated by the depth 222of the bore 218. When the prongs 214 a-b are pressed against one anotherand held in that closed position by the maintenance of the sleeve 206 inthe new position (maintained by the spring plungers in the recesses228), the semicircular extents 216 a-b move toward one another and arecorrespondingly maintained together about the cylindrical trunk 106.When the prongs 214 a-b are held in this manner, the cylindrical trunk106 cannot be removed through the mouth 213 of the now-tighter (e.g.,locked) holding enclosure 210 without the application of forcespreferably greater than will be encountered when inserting and removingthe static trial 100 from the intervertebral space during the surgicalprocedures. Once the static trial 100 has been inserted and removed fromthe intervertebral space (or the distraction spacer has been insertedand removed from the intervertebral space after being used to distractthe space), the operator can lock the holding enclosure 210 by rotatingthe sleeve 206 another quarter turn (in either the clockwise or thecounterclockwise direction). Again, if the rotation control knob 219 isrotated with enough force to cause the spring plungers to back out ofthe recesses 228, the sleeve 206 will rotate as desired. Once the sleeve206 has reached the next quarter-turn position, the spring plungers willfind the recesses 228 associated with that position, and plunge into therecesses 228 to snap the sleeve 206 into the proper position. As thesleeve 206 rotates, the sides of the sleeve's bore's inner surface moveaway from the curved outer surfaces of the prongs 214 a-b and allow theprongs 214 a-b to separate (under their own bias toward the neutralposition) as they are accommodated by the width 220 of the bore 218.When the prongs 214 a-b are separated and allowed to remain in thatposition by the maintenance of the sleeve 206 in the new position(maintained by the spring plungers in the recesses 228), thesemicircular extents 216 a-b are separated from one another and hold thecylindrical trunk 106 against falling or slipping out. That is, thecylindrical trunk 106 can be removed by the operator if the operatorapplies a sufficient force to widen the mouth 213 of the holdingenclosure 210 enough to let the cylindrical trunk 106 pass through themouth 213. Once the static trial 100 (or distraction spacer) is removed,another one can be inserted and manipulated if required.

[0100] Accordingly, the static trial holder 200 can be used to insertand remove the distraction spacers of the '127 application to distractthe intervertebral space as described in the '127, and thereafter (orduring the distraction) hold to insert and remove the static trials 100to find the appropriate size of artificial intervertebral disc to beimplanted.

[0101] A preferred embodiment of a dynamic trial of the presentinvention will now be described.

[0102] Referring now to FIGS. 3a-d, a dynamic trial of the presentinvention is shown in top (FIG. 3a), side (FIG. 3b), side cutaway (FIG.3c) and perspective (FIG. 3d) views.

[0103] The dynamic trial 300 is provided primarily for distracting anintervertebral space according to the procedures described herein and/orfor determining the appropriate size of an artificial intervertebraldisc to be implanted (or whether a particular size can be implanted)into the distracted intervertebral space. While the distraction systemsand methods described in the '127 application are also useful fordistracting an intervertebral space, the dynamic trial 300 is providedas an additional or alternate distraction tool. Further, while thestatic trials described herein as useful for determining the appropriatesize of an artificial intervertebral disc to be implanted (or whether aparticular size can be implanted), the dynamic trial 300 is provided asan additional or alternate sizing tool.

[0104] More specifically, the dynamic trial 300 includes a shaft 302having a bifurcated trial 304 at a distal end of the shaft 302. Thetrial 304 has an exterior that is preferably formed like the artificialintervertebral disc that it is meant to approximate. Accordingly, eachhalf 306 a-b of the bifurcated trial 304 has on its outwardly facingsurface a convex dome 308 a-b that is shaped like the convex dome of thecorresponding baseplate of the artificial intervertebral disc that thedynamic trial 300 approximates (e.g., the convex domes 184 a-b of thebaseplates 168 a-b of the artificial intervertebral disc 160 of FIGS.1g-n). Preferably, each convex dome 308 a-b is smooth, rather thanhaving a porous coating that is preferred for the convex domes 184 a-bof the artificial intervertebral disc 160, and each half 306 a-b doesnot have stabilizing spikes such as the stabilizing spikes 188 a-b onthe outwardly facing surfaces 186 a-b of the artificial intervertebraldisc 160. The omission of these device stabilizing and bone ingrowthencouraging structures and surfaces on the dynamic trial 300 enables thesurgeon to test the size of the artificial intervertebral disc 160 to beimplanted without invading the vertebral body endplates. The shaft 302includes an inner shaft portion 310 that centrally divides at a fulcrum311 into upper and lower distal extensions 312 a-b. The lower distalextension 312 b is fixed to the upper distal extension 312 a at thefulcrum 311, preferably by screws 313 a-b that are plug welded in place.Preferably, as shown, at least the most proximal screw 313 b extendsabove the top surface of the upper distal extension 312 a to serve as abackup stop to prevent extreme forward movement of the control knob 318that is operated to separate the distal extensions 312 a-b (describedbelow).

[0105] From the point of division to their distal ends, each of theupper and lower distal extensions 312 a-b are spring biased (preferablyby the formation of the fulcrum 311 in combination with the strength ofthe material of which the extensions 312 a-b are made, although the useof other types of springs is contemplated by the present invention)toward positions in which they converge toward one another (in thefigures, the extensions 312 a-b are shown in these positions). The lowerdistal extension 312 b is connected (preferably fixed as shown) to thelower half 306 b of the bifurcated trial 304, and the upper distalextension 312 a is connected to the upper half 306 a of the bifurcatedtrial 304. Preferably, as shown, the upper half 306 a is adjustablyconnected to the upper distal extension 312 a by a pivot pin 315 thatallows the upper half 306 a to rotate about a lateral axis that passesthrough the longitudinal and lateral center of the bifurcated trial 304.This axis of rotation allows the upper half 306 a, when separating fromthe lower half 306 b, to adjust to the orientation of the upper(adjacent) vertebral bone without causing the bone to hinge relative tothe lower vertebral bone (the bone adjacent the lower half 306 b).

[0106] In order to effect the separation of the upper and lower halves306 a-b, the shaft 302 further includes an outer shaft potion 314 thatis longitudinally translatable adjacent the inner shaft portion 310. Theouter shaft portion 314 preferably straddles the inner shaft portion 310as shown, and includes a pin 316 that passes between the distalextensions 312 a-b. The outer shaft portion 314 is preferablytranslatable distally by the forward movement of a control knob 318 nearthe proximal end of the shaft 302, and translatable proximally bybackward movement of the control knob 318. That is, when the controlknob 318 is pushed distally, the outer shaft portion 314 is movesdistally, and accordingly the pin 316 moves distally. If the pushingforce is great enough to overcome the bias of the divided extensions 312a-b (their bias toward one another), the divided extensions 312 a-b willseparate as the pin 316 moves between them (to make room for the pin316). The separation of the extensions 312 a-b will correspondinglyseparate the halves 306 a-b of the bifurcated trial 304. It should beunderstood that preferably, if the control knob 318 is released, thebias of the divided extensions 312 a-b will press against the pin 316,causing the pin 316 (and correspondingly the outer shaft portion 314 andthe control knob 318) to move proximally to allow the divided extensions312 a-b to return to their biased position, which will bring the halves306 a-b of the trial 304 back together so they can be removed from theintervertebral space. Preferably, markings 320 are provided on the innershaft portion 310 (preferably on its top surface so that the surgeon canmore easily see the markings 320) to quantify the depth (to which thebifurcated trial 304 is expanded) corresponding to the distance that theouter shaft portion 314 is translated with respect to the inner shaftportion 310.

[0107] It is anticipated that the pushing force required to separate thehalves 306 a-b will increase as they separate, due to the compression ofthe spine seeking to close the intervertebral space and the annulusseeking to prevent the adjacent vertebral discs from separating beyond acertain point. Therefore, to provide a mechanical advantage to theoperator in the event that greater distraction is required, but theoperator cannot push the control knob 318 farther with unaided humaneffort, an fine control knob 322 is provided. The fine control knob 322is preferably threaded onto the proximal end of the inner shaft portion310, proximal to the control knob 318. Thus, rotation of the finecontrol knob 322 about the longitudinal axis of the inner shaft portion310 will cause the body of the fine control knob 322 to press againstthe control knob 318 to move it farther distally. The interference ofthe threads of the fine control knob-inner shaft portion interfaceprevents the fine control knob 322 from backing up proximally unless thefine control knob 322 is reverse rotated to effect that result.

[0108] Preferably, as shown, the proximal end 324 of the shaft 302 ispreferably flanged to serve as a slap hammer for impaction (by hittingthe proximal end 324 with a mallet with a distally directed force,e.g.), if necessary for proper positioning of the bifurcated trial 304,and/or forced extraction of the bifurcated trial 304 (by hitting theflange of the proximal end 324 with a mallet with a proximally directedforce, e.g.).

[0109] Accordingly, the dynamic trial 300 can be used as an additionalor alternative distracting tool (e.g., to the distraction spacers),and/or as an alternative or additional sizing tool (e.g., to the statictrials). As an example of a use for the dynamic trial 300 as analternative or additional distraction tool and an alterative sizingtool, once the intervertebral space is distracted to (or, withoutdistraction, is at) a depth that is at least equal to the depth of theclosed bifurcated trial 304, the bifurcated trial 304 of the dynamictrial 300 can be inserted into the intervertebral space. (If theintervertebral space must be distracted initially because it starts outmore shallow than the depth of the closed bifurcated trial 304, thedistraction spacers of the '127 application and the methods disclosedtherein can be used, e.g.) The control knob 318 and/or fine control knob322 can be operated to separate the halves 306 a-b of the bifurcatedtrial 304 to distract the space as clinically appropriate. Because thebifurcated trial 304 is shaped externally to approximate the artificialintervertebral disc to be implanted (e.g., the artificial intervertebraldisc 160), and because the pivoting of the upper half 306 a of thebifurcated trial 304 allows the halves 306 a-b to appropriatelylordotically orient themselves, when the surgeon determines theintervertebral space to be distracted to its proper dimension (based onhow much compression is being experienced on the dynamic trial 300 andhow tight the annulus is), he can read the markings 320 on the shaft 302to determine what size of artificial intervertebral disc 160 is suitablefor the dimensioned intervertebral space. A subsequent bringing togetherof the halves 306 a-b and a removal of the dynamic trial 300 can then befollowed by insertion of the appropriately sized artificialintervertebral disc 160 (e.g., in a manner described below with regardto the inserter/impactor 400).

[0110] As an example of a use for the dynamic trial 300 as analternative distraction tool and an additional sizing tool, after thesurgeon has initially distracted the intervertebral space (preferablywith the distraction spacers of the '127 application), and applied oneor more of the static trials 100 to the intervertebral space todetermine the appropriate size of the artificial intervertebral disc tobe implanted (e.g., the artificial intervertebral disc 160), the surgeoncan apply the dynamic trial 300, expand it to the size of the statictrial 100 that was determined to be the appropriate size for theintervertebral space, and then further open the dynamic trial 300 for afinal sizing. An example of a final sizing that would be useful would beto test the amount of farther distraction that is clinically possible,without having to remove and replace static trials 100 when thecompression force of the spine and the tension force of the annulus areat their higher levels. Also, the surgeon may wish to distract the spaceslightly more than the size of the appropriately sized static trial 100or artificial intervertebral disc 160, so that the artificialintervertebral disc 160 can be more easily inserted after removal of thestatic 100 or dynamic trial 300 results in a compressive settling of theintervertebral space. The surgeon may also wish to distract the spaceslightly more than the size of the appropriately sized static trial 100or artificial intervertebral disc 160, to prepare it for easy insertionof the artificial intervertebral disc 160 to be implanted, withconsideration for the height of the stabilizing spikes 188 a-b on theoutwardly facing surfaces 186 a-b of the baseplates 168 a-b of theartificial intervertebral disc 160. While the artificial intervertebraldisc 160 having the spikes 188 a-b can be implanted without theadditional distraction, some surgeons may find such additionaldistraction useful or desirable for a particular case.

[0111] A preferred embodiment of an inserter/impactor of the presentinvention will now be described.

[0112] Referring now to FIGS. 4a-d, an inserter/impactor of the presentinvention is shown in side (FIGS. 4a), top (FIG. 4b), side cutaway (FIG.4c) and perspective (FIG. 4d) views. FIGS. 4e-h show side (FIG. 4e), top(FIG. 4i), side cutaway (FIG. 4g), and perspective (FIG. 4h) views of aninserter/impactor of the present invention holding a static trial of thepresent invention. FIGS. 4i-j show top views of an inserter/impactor ofthe present invention holding a static trial of the present invention intwo alternative ways. FIGS. 4k-n show side (FIG. 4k), top (FIG. 4l),side cutaway (FIG. 4m), and perspective (FIG. 4n) views of aninserter/impactor of the present invention holding an exemplaryartificial intervertebral disc of the present invention. FIGS. 4o-p showtop views of an inserter/impactor of the present invention holding anexemplary artificial intervertebral disc of the present invention in twoalternative ways.

[0113] The inserter/impactor 400 is provided primarily for holding,inserting, repositioning, removing, impacting, extracting, and otherwisemanipulating an artificial intervertebral disc having features suitablefor being manipulated by the inserter/impactor. (However, it can also beused to hold, insert, reposition, remove, impact, extract, and otherwisemanipulate the static trials 100 as described above, as well as anyother orthopedic device having suitable features therefor.) Exemplarysuitable artificial intervertebral discs include, but are not limitedto, the artificial intervertebral disc 160 described herein and theartificial intervertebral discs described in the '160 application withregard to FIGS. 8a-y, 9 a-t, 10 a-t, 11 a-j, and 12 a-o thereof and bythe accompanying descriptions therefor (e.g., embodiments identified asthe first, second, third, fourth, and fifth preferred embodiments of thefourth embodiment family, etc.). Regarding the features suitable forbeing manipulated by the inserter/impactor 400, such features includethose discussed above as being suitable features on the static trials100 and disc 160, namely, an anteriorly facing flat surface on thesecond (e.g., lower) baseplate of the trial or disc, flanked by twoanteriolaterally facing flat surfaces (one on each side of theanteriorly facing flat surface), and, to provide for holding of thetrial or disc for an anterior insertion approach, a hole spaced from theanteriorly facing flat surface, the hole having a longitudinal axisparallel to the anteriorly facing flat surface.

[0114] More particularly, the inserter/impactor 400 includes a shaft 402having a distal end 404 that has angled flat surfaces 420 a-ccorresponding to and fittable against angled flat surfaces of the statictrial (e.g., the surfaces 120 a-c of the static trial 100) or artificialintervertebral disc (e.g., the surfaces 180 a-c of the artificialintervertebral disc 160) to be implanted. For example, in an anteriorapproach for the trial 100 (as shown in FIGS. 4e-h), 120 a and 120 dfacing 420 a, 120 b and 120 e facing 420 b, and 120 c and 120 f facing420 c, and in an anterior approach for the disc 160 (as shown in FIGS.4k-n), 180 a and 180 d facing 420 a, 180 b and 180 e facing 420 b, and180 c and 180 f facing 420 c.

[0115] Further, the inserter/impactor 400 includes a holding pin 408that extends from the center flat surface 420 b along a longitudinalaxis of the shaft 402, the pin 408 having a distal end 410 that bendsdownward. The holding pin 408 is spring loaded (by a spring 409) in acentral channel of the shaft 402, so that it is biased toward andagainst the central flat surface 420 b (preferably, the bent end 410 ofthe pin 408 prevents it from entering the central channel).

[0116] A flange 411, mechanically connected to the pin 408 andtranslating adjacent the shaft 402, can be pushed distally to overcomethe bias of the spring 409 to space the pin 408 away from the centralflat surface 420 b. In this position, the pin 408 can be inserted in thehole 120 b, 180 b in the baseplate 108 b, 168 b of the static trial 100or artificial intervertebral disc 160. Releasing the flange 411 allowsthe spring 409 to pull the pin 408 back, causing the anteriorly facingsurface 120 b, 180 b of the baseplate 108 b 168 b to be held against thecentral flat surface 420 b of the inserter/impactor 400 and theanterioloaterally facing flat surfaces 120 a,c, 180 a,c of the statictrial 100 or artificial intervertebral disc 160 to be held against theother corresponding flat surfaces 420 a,c of the inserter/impactor 400.A knob 412, threaded on the shaft 402, can be rotated about thelongitudinal axis of the shaft 402 to push the flange 411 fartherproximally, to pull the pin 409 tighter and therefore lock its position(the interference of the threads of the knob-shaft interface preventsthe knob 412 from moving distally unless the knob 412 is reverse rotatedto effect that result) to more securely hold the baseplate 108 b,168 b,and reverse rotated to unlock and loosen the pin 409.

[0117] When the static trial 100 or disc 160 is held in this manner,rotation of the static trial 100 or disc 160 about a longitudinal axis(of the static trial 100 or disc 160) relative to the inserter/impactor400 is prevented by interference of the corners of the static trial's100 or disc's 160 flat surfaces 120 a-c,180 a-c and the corners of theinserter/impactor's 400 flat surfaces 420 a-c, similar to the manner inwhich a wrench holding a nut prevents rotation of the nut relative tothe wrench. Further, the holding of the static trial 100 or disc 160 inthis manner allows for some repositioning of the static trial 100 ordisc 160 in the intervertebral space via rotation of the static trial100 or disc 160 in either direction about the longitudinal axis of theintervertebral space.

[0118] Preferably, both of the baseplates of the static trial 100 ordisc 160 have similarly configured flat surfaces. For example, the lowerbaseplate's 108 b,168 b flat surfaces 120 a-c,180 a-c have similarlyconfigured and similarly oriented counterpart flat surfaces 120 d-f,180d-f on the upper baseplate 108 a,168 a. Further preferably, bothbaseplates' 108 a-b,168 a-b flat surfaces 120 a-f,180 a-f face theangled flat surfaces 420 a-c of the inserter/impactor 400 when thestatic trial 100 or disc 160 is held by the inserter/impactor 400. Forexample, in an anterior approach for the trial 100 (as shown in FIGS.4e-h), 120 a and 120 d facing 420 a, 120 b and 120 e facing 420 b, and120 c and 120 f facing 420 c, and in an anterior approach for the disc160 (as shown in FIGS. 4k-n), 180 a and 180 d facing 420 a, 180 b and180 e facing 420 b, and 180 c and 180 f facing 420 c.

[0119] It should be noted that preferably, when the static trial 100 isheld by the inserter/impactor 400, the flat surfaces 120 a-c and thecounterpart flat surfaces 120 d-f are tightly held against the angledflat surfaces 420 a-c of the inserter/impactor 400 as described above.It is also preferable that the baseplates 108 a-b of each of theplurality of static trials 100 be appropriately lordotically angledrelative to one another to ease insertion of the static trial 100 intothe intervertebral space and to mimic how the artificial intervertebraldisc 160 will typically be oriented as it is being inserted using theinserter/impactor 400, and to ease insertion of the static trial 100into the intervertebral space. While not shown in FIGS. 1a-f, in someembodiments, when the static trials 100 are formed in such alordotically oriented configuration, it is preferable that the flatsurfaces 120 d-f on the first (e.g., upper) baseplate 108 a be parallelto the flat surfaces 120 a-c of the second (e.g., lower) baseplate 108 bin the static trial's 100 appropriately lordotically orientedconfiguration, so that when the static trial 100 is held tightly by theinserter/impactor 400, the flat surfaces 120 a-f are flush with the flatsurfaces 420 a-c of the inserter/impactor 400 even though the baseplates108 a-b are lordotically angled with respect to one another.

[0120] By contrast, preferably, when the artificial intervertebral disc160 is held by the inserter/impactor 400, the flat surfaces 180 a-c aretightly held against the angled flat surfaces 420 a-c of theinserter/impactor 400 as described above, but the counterpart flatsurfaces 180 d-f are loosely held against the angled flat surfaces 420a-c of the inserter/impactor 400. As such, the structure of theartificial intervertebral disc 160 having the counterpart flat surfaces180 d-f (e.g., the upper baseplate 168 a) is able to angulate and rotateto a limited extent relative to the structure of the artificialintervertebral disc 160 having the flat surfaces 180 a-c. This permitsthe artificial intervertebral disc 160 to adjust to the intervertebralspace (e.g., to the angulation of the adjacent vertebral endplates,defining the intervertebral space, relative to one another) as it isbeing inserted thereinto. That is, typically, the adjacent vertebralendplates will be lordotically angled with respect to one another as aresult of the intervertebral space being prepared and distracted. As theartificial intervertebral disc 160 is then inserted into theintervertebral space using the inserter/impactor 400, then, thebaseplates 168 a-b will be permitted to lordotically angle with respectto one another to squeeze into the intervertebral space.

[0121] Also preferably, in order to provide for a holding of the statictrial 100 or disc 160 for two additional (here, anteriolateral)insertion approaches, each static trial 100 or disc 160 also includestwo additional holes 122 a,182 a and 122 c,182 c, one (e.g., 122 a,182a) spaced apart from one of the anteriolaterally facing flat surfaces(e.g., 120 a,180 a), and the other (e.g., 122 c,182 c) spaced apart fromthe other of the anteriolaterally facing flat surfaces (e.g., 120 c,180c). Accordingly, operation of the inserter/impactor 400 can fit theholding pin 408 into either of these two additional holes 122 a,182 a or122 c,182 c, and hold the associated anteriolaterally facing flatsurface (the one associated with the hole into which the pin 408 is fit)of the static trial 100 or disc 160 against the flat surface of theinserter/impactor 400 opposite the pin 408. For example, as discussedbelow with regard to the inserter/impactor 400, in a firstanteriolateral approach for the trial 100 (as shown in FIG. 4i), 120 aand 120 d facing 420 b, 120 b and 120 e not confronted, and 120 c and120 f facing 420 a, and a first anteriolateral approach for the disc 160(as shown in FIG. 4o), 180 a and 180 d facing 420 b, 180 b and 180 e notconfronted, 180 c and 180 f facing 420 a. And, for example, as discussedbelow with regard to the inserter/impactor 400, in a secondanteriolateral approach for the trial 100 (as shown in FIG. 4j), 120 aand 120 d facing 420 c, 120 b and 120 e facing 420 a, and 120 c and 120f not confronted, and a second anteriolateral approach for the disc 160(as shown in FIG. 4p), 180 a and 180 d facing 420 c, 180 b and 180 efacing 420 a, 180 c and 180 f not confronted.

[0122] It should be understood that preferably, in order to facilitatethese additional approaches, the angle separating the anteriorly facingflat surface of the static trial 100 or disc 160 and one of theanteriolaterally facing flat surfaces of the static trial 100 or disc160 is equal to the angle separating the anteriorly facing flat surfaceand the other of the anteriolaterally facing flat surfaces. Preferably,the surfaces are angled with respect to one another at an angle of 33.4degrees.

[0123] It should also be understood that the inclusion of additionaladjacent angulated surfaces (or placing the angulated surfaces in otherlocations on the trial or disc), and/or including corresponding holesadjacent to such surfaces, can provide the surgeon with additionalapproaches, e.g., other anteriolateral approaches, directly lateralapproaches, posteriolateral approaches, and/or directly posteriorapproaches. For example, a trial or disc can have angled surfaces (andcorresponding holes) along the entire perimeter of one or both of thebaseplates, and thus enable the surgeon to engage the trial or disc froma number of angles, including anterior, posterior, lateral,anteriolateral, and posteriolateral angles.

[0124] The inserter/impactor 400 further includes at a proximal end acap 414 for use as an impact surface if the trial 100 or disc 160 mustbe impacted further into the intervertebral space after insertion, orforcibly extracted from the intervertebral space. A mallet can be usedto strike the cap 414 (in a distal direction for impaction, or in aproximal direction (using the flange of the cap 414) for extraction). Itshould be noted a striking of the cap 414 will translate the strikingforce to the baseplates through the shaft 402 and the flat surfaces, butwill not damage the holding pin 408 because the holding pin 408 isspring loaded in the central channel and thus buffered from the strikingforce thereby.

[0125] Accordingly, the inserter/impactor 300 can be used to grip eitherthe static trials or the artificial intervertebral disc to be implanted,and hold the same during insertion and/or removal of the same, and isuseful for, a variety of surgical approach angles.

[0126] Preferred embodiments of a repositioner/extractor of the presentinvention will now be described.

[0127] Referring now to FIGS. 5a-c, a symmetric repositioner/extractorof the present invention is shown in side (FIG. 5a), top (FIG. 5b), andperspective (FIG. 5c) views. And referring now to FIGS. 5d-f, an offsetleft repositioner/extractor of the present invention is shown in side(FIG. 5d), top (FIG. 5e), and perspective (FIG. 5f) views. And referringnow to FIGS. 5g-i, an offset right repositioner/extractor of the presentinvention is shown in side (FIG. 5g), top (FIG. 5h), and perspective(FIG. 5i) views. And referring now to FIGS. 5j-l, an alternative offsetleft repositioner/extractor of the present invention is shown in side(FIG. 5j), top (FIG. 5k), and perspective (FIG. 5l) views. And referringnow to FIGS. 5m-o, an alternative offset right repositioner/extractor ofthe present invention is shown in side (FIG. 5m), top (FIG. 5n), andperspective (FIG. 5o) views.

[0128] Each repositioner/extractor is provided primarily forrepositioning and/or extracting a static trial or artificialintervertebral disc having features suitable for being manipulated bythe repositioner/extractor. Exemplary suitable artificial intervertebraldiscs are described in the '160 application with regard to FIGS. 8a-y, 9a-t, 10 a-t, 11 a-j, and 12 a-o thereof and by the accompanyingdescriptions therefor (e.g., embodiments identified as the first,second, third, fourth, and fifth preferred embodiments of the fourthembodiment family, etc.). Regarding the features suitable for beingmanipulated by each repositioner/extractor, such features include atleast two holes extending longitudinally into one of the baseplates ofthe static trial or artificial intervertebral disc from the inwardlyfacing surface of the baseplate. More than two holes can be used toprovide for multiple repositioning/extracting approaches. Preferably, inorder for the same repositioning/extracting tool to be used for multipleapproaches on the same trial or artificial intervertebral disc, adjacentholes should be separated by the same distance separating other adjacentholes.

[0129] In order to engage the two holes, each repositioner/extractor hastwo pins extending in parallel from a central shaft, perpendicular tothe longitudinal axis of the central shaft. The pins are spaced toengage the two holes simultaneously, and each pin has a diameter smallerthan the diameter of the hole it is to engage. Therefore, the pins canbe inserted into the holes, and pulling or pushing on the central shaftalong its longitudinal axis when the holes are engaged pulls or pushesthe static trial or artificial intervertebral disc in the intervertebralspace. Further, because two holes are engaged, the static trial orartificial intervertebral disc can be rotated in either direction abouta longitudinal axis passing through the intervertebral space, byrotating of the central shaft of the repositioner/extractor about itsdistal end, about an axis parallel to the longitudinal axes of the pins.A handle at a proximal end of the central shaft is useful for pushing orpulling on the shaft. A flange adjacent the proximal end of the shaft isuseful for impaction (either with a distally directed force or aproximally directed force), if necessary to manipulate the shaft.

[0130] On each repositioner/extractor, the pins are formed on prongsthat extend laterally from the central shaft. The direction of theprongs, and the location of the pins relative to the central shaft,determine the angle or angles of surgical approach for which aparticular repositioner/extractor can be used. Further, the number andlocation of holes further determine the angle or angles of surgicalapproach for which a particular repositioner/extractor can be used.Accordingly, the present invention contemplates a variety ofrepositioner/extractors, and a variety of holes configurations, toprovide the surgeon with a variety of possible surgical approach angles.

[0131] For example, three repositioner/extractors are illustrated, and,for example, two hole configurations are illustrated.

[0132] The first, symmetric, repositioner/extractor 500, shown in FIGS.5a-c, includes a shaft 502 having a distal end that is symmetricallydivided into two prongs 504 a-b, each of the prongs having a pin 506 a-bextending upwardly and parallel to the pin on the other prong. Thesecond and third, left offset and right offset, repositioners/extractors510,520, shown in FIGS. 5d-f and 5 g-i, respectively, each include ashaft 512,522 having a distal end that bends diagonally laterally, theleft offset distal end 514 bending in one direction (e.g., to the left),the right offset distal end 524 bending in an opposite direction (e.g.,to the right). The distal end of each of the second and thirdrepositioners/extractors 510,520 has two pins 516 a-b,526 a-b seriallyspaced on the bent portion, and each of the pins extends upwardly andparallel to the other pin. (As shown in FIGS. 5j-l and 5 m-o,alternative embodiments 530,540 of the second and third, left offset andright offset, repositioners/extractors each include a shaft 532,542having a distal end that has a straight prong 534 a,544 a and a curvedlateral prong 534 b,544 b, where the curved lateral prong 534 b extendsin one direction (e.g., left) for the alternative left offsetrepositioner/extractor 530, and where the curved lateral prong 544 bextends in an opposite direction (e.g., right) for the alternative rightoffset repositioner/extractor 540. Each of the prongs 534 a-b,544 a-bhas a pin 536 a-b,546 a-b extending upwardly and parallel to the pin onthe other prong. The alternative repositioners/extractors 530,540, eachhaving a space between the pins 536 a,b,546 a,b, provides for avoidanceof any structures on the static trial or artificial intervertebral discthat may be present between the holes.) On each of therepositioners/extractors 500, 510, 520, 530, 540, the pins are spaced sothat they simultaneously each fit into a respective one of the twoadjacent holes in the baseplate of the static trial or artificialintervertebral disc. Each of the repositioners/extractors 500, 510, 520,530, 540 has a handle 508, 518, 528, 538, 548 at a proximal end of thecentral shaft which is useful for pushing or pulling on the shaft, and aflange 509, 519, 529, 539, 549 adjacent the proximal end of the shaftthat is useful for impaction (either with a distally directed force or aproximally directed force), if necessary to manipulate the shaft.

[0133] As noted above, the repositioner/extractor that is appropriate ordesired for a given case depends at least in part on the configurationof the holes in the baseplates. Two hole configurations are disclosed,as examples of suitable configurations, although other configurationsare possible and contemplated by the present invention. A first holeconfiguration includes three holes on one of the baseplates, the holesbeing configured so that a first hole is located in theanterior-posterior plane, and the adjacent (second and third) holes arelocated in respective opposing anteriolateral planes on either side ofthe first hole. This hole configuration is shown in FIGS. 5p-u, each ofwhich shows a top cutaway view of the artificial intervertebral disc ofFIGS. 1g-n, showing its lower baseplate, having the first holeconfiguration, engaged by one of the repositioners/extractors500,510,520. Each view of the lower baseplate shows the first hole 550,the second hole 552, and the third hole 554 of the first holeconfiguration.

[0134] A second hole configuration includes four holes on one of thebaseplates, the holes being configured so that first and second holesstraddle the anterior-posterior plane, a third hole is located so thatthe third hole and the first hole straddle one of the opposinganteriolateral planes, and a fourth hole is located so that the fourthhole and the second hole straddle the other of the opposinganteriolateral planes. This hole configuration is shown in FIGS. 5v-dd,each of which shows a bottom cutaway view of the artificialintervertebral disc of FIGS. 1g-n, showing its upper baseplate, havingthe second hole configuration, engaged by one of therepositioners/extractors 500,510,520. Each view of the upper baseplateshows the first hole 560, the second hole 562, the third hole 564, andthe fourth hole 566, of the second hole configuration.

[0135] It should be understood that configurations having more or fewerholes, and in a variety of locations, are contemplated by the invention,and the detailed descriptions of only two hole configurations is notmeant to limit the invention to only these two configurations.Importantly, the invention encompasses using a hole or any number ofholes, bored at any suitable angle, whether parallel to other holes ornot, in any number of locations on a spacer, a trial or an artificialintervertebral disc (not limited to locations on the baseplates), forpurposes of enabling the spacer, trial, or disc to be gripped by amanipulation instrument (not limited to a repositioner/extractor) thatengages the hole, and/or to enable the surgeon to work from a variety ofapproaches. For example, as described in more detail below, the firstand second hole configurations described herein, in cooperation with therepositioner/extractors, provide the surgeon with the ability to workfrom a directly anterior approach, as well as several anteriolateralapproaches. It should be understood that additional hole configurationscan enable the surgeon to work from a directly posterior approach,posteriolateral approaches, directly lateral approaches, oranteriolateral approaches that are different that those illustrated. Forexample, the placement of one or more suitably spaced holes (or theaddition of one or more holes) on the posterior edge, and/or one or bothof the lateral edges of one or both of the baseplates, would enable thesurgeon to use the repositioner/extractors of the present invention toachieve such approaches.

[0136] As noted above, and referring now to FIGS. 5p-dd, it can be seenthat each of the repositioner/extractors can be used in more than onemanner depending on the tool desired and the approach desired. Forexample, with reference to FIGS. 5p-q, regarding the first holeconfiguration (three holes in one of the baseplates), the symmetricrepositioner/extractor 500 can be used in either of two anteriolateralapproaches (see FIGS. 5p-q). That is, the symmetricrepositioner/extractor's shaft 502 can be inserted into the wound fromeither of the two anteriolateral approaches, and the pins 506 a-b can beinserted into the first 550 and second 552 holes (for one of the twoanteriolateral approaches) (FIG. 5p) or the first 550 and third 552holes (for the other of the two anteriolateral approaches) (FIG. 5q) ofthe first hole configuration.

[0137] Also, for example, with reference to FIGS. 5r-u, regarding thefirst hole configuration, each of the left offset repositioner/extractor510 and the right offset repositioner/extractor 520 can be used ineither a directly anterior approach (FIGS. 5r,t) or a respectiveanteriolateral approach (FIGS. 5s,u). That is, the right offsetrepositioner/extractor's shaft 522 can be inserted into the wound from adirect anterior approach, and the right offset repositioner/extractor'spins 526 a-b can then be placed into the first 550 and second 552 holesof the first hole configuration (FIG. 5r). And, the right offsetrepositioner/extractor's shaft 522 can be inserted into the wound froman anteriolateral approach, and the right offsetrepositioner/extractor's pins 526 a-b can then be placed into the first550 and third 554 holes of the first hole configuration (FIG. 5s). And,the left offset repositioner/extractor's shaft 512 can be inserted intothe wound from a direct anterior approach, and the left offsetrepositioner/extractor's pins 516 a-b can then be placed into the first550 and third 554 holes of the first hole configuration (FIG. 5t). And,the left offset repositioner/extractor's shaft 512 can be inserted intothe wound from an anteriolateral approach, and the left offsetrepositioner/extractor's pins 516 a-b can then be placed into the first550 and second 552 holes of the first hole configuration (FIG. 5u). Itshould be noted that the alternate left offset 530 and alternate rightoffset 540 repositioners/extractors can also fit into the holes of thefirst hole configuration in the same manner as described here withregard to the left offset 510 and right offset 520repositioners/extractors.

[0138] Also, for example, with reference to FIGS. 5v-dd, regarding thesecond hole configuration (four holes in one of the baseplates), thesymmetric repositioner/extractor 500 can be used in a directly anteriorapproach (FIG. 5v), and either of two anteriolateral approaches (FIGS.5w-x). That is, the symmetric repositioner/extractor's shaft 502 can beinserted into the wound from a directly anterior approach, and the pins506 a-b can be inserted into the first 560 and second 562 holes of thesecond hole configuration (FIG. 5v). And, the symmetricrepositioner/extractor's shaft 502 can be inserted into the wound fromeither of the two anteriolateral approaches, and the pins 506 a-b can beinserted into the first 560 and third 564 holes (for one of the twoanteriolateral approaches) (FIG. 5w) or the second 562 and fourth 566holes (for the other of the two anteriolateral approaches) (FIG. 5x) ofthe second hole configuration.

[0139] Also, for example, with reference to FIGS. 5y-dd, regarding thesecond hole configuration, each of the left offsetrepositioner/extractor 510 and the right offset repositioner/extractor520 can be used in any of three respective anteriolateral approaches.That is, the right offset repositioner/extractor's shaft 522 can beinserted into the wound from any of its three possible anteriolateralapproaches, and the right offset repositioner/extractor's pins 526 a-bcan then be placed into the first 560 and second 562 holes (FIG. 5y)(for a first of the three anteriolateral approaches), the first 560 andthird 564 holes (FIG. 5z) (for a second of the three anteriolateralapproaches), or the second 562 and fourth 566 holes (FIG. 5aa) (for athird of the three anteriolateral approaches). And, the left offsetrepositioner/extractor's shaft 512 can be inserted into the wound fromany of its three possible anteriolateral approaches, and the left offsetrepositioner/extractor's pins 516 a-b can then be placed into the first560 and second 562 holes (FIG. 5bb) (for a first of the threeanteriolateral approaches), the first 560 and third 564 holes (FIG. 5cc)(for a second of the three anteriolateral approaches), or the second 562and fourth 566 holes (FIG. 5dd) (for a third of the three anteriolateralapproaches). It should be noted that the alternate left offset 530 andalternate right offset 540 repositioners/extractors can also fit intothe holes of the second hole configuration in the same manner asdescribed here with regard to the left offset 510 and right offset 520repositioners/extractors.

[0140] It should be noted from the illustrations in FIGS. 5p-dd that theanteriolateral approaches are at a variety of angles relative to theanterior-posterior plane, and further that the illustrated angles aremerely exemplary. That is, the invention encompasses additional approachangles, in that such additional approach angles are possible by (asdescribed above) adding or deleting holes, and/or changing the locationof holes, and/or changing the spacing between holes (in conjunction withchanging the spacing between pins), and/or changing the angle at whichthe offset repositioner/extractors' pins are placed relative to oneanother and to the shaft of such repositioner/extractors.

[0141] As discussed above, once the pins are established in the twoadjacent holes, manipulating the shaft of the repositioner/extractorwill reposition the static trial or artificial intervertebral disc inthe intervertebral space and/or extract it from the intervertebralspace. The use of more than one pin (versus one pin) enables the statictrial or artificial intervertebral disc to be rotated in eitherdirection about a longitudinal axis passing through the intervertebralspace.

[0142] A preferred embodiment of a leveler of the present invention willnow be described.

[0143] Referring now to FIGS. 6a-e, a leveler of the present inventionis shown in bottom (FIG. 6a), side (FIG. 6b), front (FIG. 6c), toppartial perspective (FIG. 6d), and bottom partial perspective (FIG. 6e)views. More particularly, FIG. 6d shows a top perspective view of thedistal end of the leveler, and FIG. 6e shows a bottom perspective viewof the distal end of the leveler.

[0144] The leveler is provided primarily for establishing a parallelorientation of the baseplates (relative to one another), and/or securingthe purchase of the stabilizing spikes, of an artificial intervertebraldisc having features suitable for being manipulated by the leveler.Exemplary suitable artificial intervertebral discs are described in the'160 application with regard to FIGS. 8a-y, 9 a-t, 10 a-t, 11 a-j, and12 a-o thereof and by the accompanying descriptions therefor (e.g.,embodiments identified as the first, second, third, fourth, and fifthpreferred embodiments of the fourth embodiment family, etc.). Regardingthe features suitable for being manipulated by the leveler, suchfeatures include suitably formed inwardly facing surfaces of thebaseplates of the artificial intervertebral disc.

[0145] More particularly, the leveler 600 includes a shaft 602 having aforked distal end formed by two opposing tongs 604 a-b that aresymmetric to one another about a longitudinal axis of the shaft 602.Each of the tongs 604 a-b has an extent that initially curves laterallyoutward away from the shaft 602 and from the other tong's extent, todefine a central pocket 606 forward of the shaft 602 between the tongs'extents. Each tong's extent then resumes a distal direction to becomeparallel to the shaft 602 and to the other tong's extent.

[0146] Each tong's extent has an upper surface 608 a-b and a lowersurface 610 a-b. The upper surface 608 a-b is preferably shaped toconform against the inwardly facing surface of a first (e.g., upper)baseplate of an artificial intervertebral disc, and the lower surface610 a-b is preferably shaped to conform against the inwardly facingsurface of a second (e.g., lower) baseplate of the artificialintervertebral disc, so that insertion of the forked distal end of theleveler 600 between the baseplates, with the central pocket 606 of thedistal end avoiding the central portion of the artificial intervertebraldisc, and with the upper 608 a-b and lower surfaces 610 a-b so engagingthe inwardly facing surfaces of the baseplates, causes the baseplates tobe placed in parallel orientation with respect to one another.

[0147] More particularly, for example for use with the exemplaryartificial intervertebral disc of FIGS. 1g-n, the upper surface 608 a-bof each extent is flat, except for a tapered section 612 a-b at thedistal tip of the extent, which tapered section narrows the tip, and thelower surface 610 a-b of each extent is curved to form opposing concavecontours 614 a-b that are cooperatingly shaped to conform against theinwardly facing surface of the convex structure of the artificialintervertebral disc.

[0148] The preferred use of the leveler 600 is as follows. As discussedabove, once the intervertebral space has been prepared and distracted toa dimension that will accept the artificial intervertebral disc to beimplanted, the artificial intervertebral disc 160 is engaged at itslower baseplate 168 b by the inserter/impactor 400 discussed above.During insertion (and, if necessary, impaction) of the artificialintervertebral disc 160 into the intervertebral space, the upperbaseplate 168 a remains free to angulate with respect to the lowerbaseplate 168 b, so that the angulation of the baseplates conforms tothe angulation of the intervertebral space as the artificialintervertebral disc is being inserted thereinto. Typically, theendplates of the prepared and distracted intervertebral space will belordotically angled with respect to one another, due to the use of thestatic trials 100 as described above, which are formed to have alordotic taper as discussed above. Thus, when the artificialintervertebral disc is inserted into the intervertebral space, itsbaseplates will be lordotically angled with respect to one another. Oncethe artificial intervertebral disc 160 is inserted, theinserter/impactor 400 can be disengaged, and the repositioner/extractors500, 510, 520, 530, 540 discussed above can be applied to the artificialintervertebral disc, if necessary to achieve a more optimal positioning.

[0149] Once the positioning is established, the leveler 600 ispreferably applied to the artificial intervertebral disc 160. The forkeddistal end of the leveler 600 is inserted so that the extents 604 a-bare placed between the inwardly facing surface 164 a of the upperbaseplate 168 a and the inwardly facing surface 164 b of the convexstructure 162 on the lower baseplate 168 b, and so that the centralpocket 606 of the leveler 600 avoids the ball-and-socket joint of theartificial intervertebral disc 160. If the baseplates are lordoticallyangled with respect to one another, the tapered sections 612 a-b of theupper surfaces 608 a-b of the forked distal end will be approximatelyparallel to, and will first encounter, the angled inwardly facingsurface 164 a of the upper baseplate 168 a. At the same time, theconcave contours 614 a-b of the lower surfaces 610 a-b will accommodatethe inwardly facing surface 164 b of the convex structure 162 on thelower baseplate 168 b. As the tapered sections 612 a-b press against theinwardly facing surface 164 a of the upper baseplate 168 a, and theconcave contours 614 a-b slip into place against the inwardly facingsurface 164 b of the convex structure 162 on the lower baseplate 168 b,the tapers 612 a-b will function as wedges to force the posteriorportion of the upper baseplate 168 a away from the posterior portion ofthe lower baseplate 168 b. Accordingly, as the posterior portions arebeing separated, the stabilizing spikes 188 a-b on the outwardly facingsurfaces 186 a-b of the baseplates 168 a-b find or secure their purchasein the hard bone of the outer ring of the vertebral body endplates. Whenthe forked distal end is fully seated (stops 616 a-b are provided tobutt up against the anterior portions of the baseplates 168 a-b toprevent the forked distal end from being inserted too far), the extentsof the tongs 604 a-b hold the baseplates 168 a-b parallel to oneanother, and so that the spikes 188 a-b are fully engaged in theendplates. The surgeon then slips the leveler 600 out from between thebaseplates 168 a-b, and out from the wound and completes the procedure.A handle 618 is provided at a proximal end of the shaft 602 for pushing,pulling, and otherwise manipulating the leveler 600 as needed.

[0150] While there has been described and illustrated specificembodiments of instrumentation, it will be apparent to those skilled inthe art that variations and modifications are possible without deviatingfrom the broad spirit and principle of the invention. The invention,therefore, shall not be limited to the specific embodiments discussedherein.

What is claimed is:
 1. An apparatus for at least one of distracting anintervertebral space and determining a size of an artificialintervertebral disc to be implanted in the intervertebral space, theapparatus comprising: a shaft; at least two distal extensions coupled tothe shaft; a bifurcated trial having a first trial half of thebifurcated trial coupled to a first of the extensions and having asecond trial half of the bifurcated trial coupled to a second of theextensions; and a pin located between the extensions; wherein at leastone external trial shape of the bifurcated trial approximates at leastone external disc shape of a corresponding portion of the artificialintervertebral disc; wherein movement of the pin in a distal directionincreases a separation between the extensions; wherein movement of thepin in a proximal direction decreases the separation between theextensions; and wherein varying the separation between the extensionsvaries a separation between the trial halves.
 2. The apparatus of claim1, wherein at least one of the trial halves pivots to place the trialhalves in lordosis.
 3. The apparatus of claim 1, wherein at least one ofthe trial halves has an outwardly facing trial surface shaped as aconvex dome.
 4. The apparatus of claim 1, wherein at least one of thetrial halves has a smooth outwardly facing trial surface.
 5. Theapparatus of claim 1, wherein at least one of the trial halves has anoutwardly facing trial surface that approximates a correspondingoutwardly facing disc surface of the artificial intervertebral disc. 6.The apparatus of claim 1, further comprising at least one marking,wherein the marking quantifies at least one of the group consisting of afirst distance between respective inner surfaces of the trial halves, asecond distance between respective outer surfaces of the trial halves,and the size of the artificial intervertebral disc to be implanted inthe intervertebral space.
 7. The apparatus of claim 6, wherein themarking is located on the shaft.
 8. The apparatus of claim 6, wherein atleast one of the markings quantifies an artificial intervertebral discsize in a range of 13 mm to 20 mm.
 9. The apparatus of claim 1, furthercomprising at least one flange coupled to a proximal shaft end of theshaft; wherein applying pressure to the flange in a distal directionaids insertion of the bifurcated trial into the intervertebral space;and wherein applying pressure to the flange in a proximal direction aidsextraction of the bifurcated trial from the intervertebral space. 10.The apparatus of claim 1, wherein at least one of the extensions iscoupled to a fulcrum of the shaft.
 11. The apparatus of claim 1, whereinat least one of the extensions is biased toward the other of theextensions.
 12. The apparatus of claim 11, wherein the bias is createdby at least one of the group consisting of a spring, a material of atleast one of the extensions, a strength of the material, and formationof a fulcrum that is located at a proximal end of at least one of theextensions.
 13. The apparatus of claim 1, wherein at least one of thetrial halves is pivotally coupled to its corresponding extension suchthat the trial half pivots about an axis perpendicular to a longitudinalaxis of the extension passing through the bifurcated trial; and whereinthe pivoting of the trial half allows the trial half to adjust to theorientation of a vertebral bone when the trial half is inserted into theintervertebral space such that relative hinging of adjacent vertebralbones is minimized.
 14. The apparatus of claim 1, wherein at least oneof the extensions is coupled to the shaft via at least one screw suchthat the screw limits adjustment of the pin.
 15. The apparatus of claim1, further comprising an outer shaft portion coupled to the pin andextending adjacent at least one of the group consisting of a portion ofthe shaft, and a portion of one of the extensions.
 16. The apparatus ofclaim 15, further comprising a control device coupled to at least one ofthe outer shaft portion and the pin; wherein movement of the controldevice varies the separation of the trial halves.
 17. The apparatus ofclaim 16, wherein the control device is a first control device, andfurther comprising a second control device, wherein the second controldevice maintains the trial halves at the separation created byadjustment of the first control device.
 18. The apparatus of claim 17,wherein at least one of the control devices is a knob.
 19. The apparatusof claim 17, wherein the second control device is threaded to at least aportion of the shaft; and wherein interference between second controldevice threads of the second control device and shaft threads of theshaft holds the extensions at the separation created by adjustment ofthe first control device.
 20. The apparatus of claim 17, whereinrotation of the second control device increases the separation betweenthe trial halves; and wherein reverse rotation of the second controldevice decreases the separation between the trial halves.